TIL

Today I Learned

A collection of concise write-ups on small things I learn day to day across a variety of languages and technologies. These are things that don't really warrant a full blog post. These are things I've picked up by Learning In Public™ and pairing with smart people at Hashrocket.

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1176 TILs and counting...

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Categories

• Ack
• Amplify
• Chrome
• Clojure
• CSS
• Deno
• Devops
• Elixir
• Gatsby
• Git
• GitHub Actions
• Go
• HTML
• HTTP
• Internet
• JavaScript
• jq
• Kitty
• Linux
• Mac
• MongoDB
• MySQL
• Netlify
• Next.js
• Phoenix
• PostgreSQL
• Python
• Rails
• React
• React Native
• React Testing Library
• ReasonML
• RSpec
• Ruby
• sed
• Shell
• Tailwind CSS
• tmux
• TypeScript
• Unix
• Vercel
• Vim
• VSCode
• Webpack
• Workflow
• XState
• YAML

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Ack

• ack --bar
• Case-Insensitive Search
• List Available File Types

Amplify

• Sign Up User With Email And Password

Chrome

• Access A Value Logged To The Console
• Chrome Supports Many Unix Keyboard Shortcuts
• Copy Some Data From The Console
• Duplicate The Current Tab
• Easier Access To Network Throttling Controls
• Keybinding To Focus The Address Bar
• Navigate The Browser History With Vimium
• Pretty Print Tabular Data
• Reference The Selected Node
• Selecting DOM Elements Faster Than Ever
• Simulating Various Connection Speeds
• Toggle Device Mode
• Toggle Open The Console Drawer
• View Network Traffic For New Tabs

Clojure

• Aggregation Using merge-with
• Argument Requirements For A Function
• Combinations Of Items From A Sequence
• Define Something Only Once
• Evaluate One Liners With lein-exec
• Expanding Macros
• Get The Value Of An Environment Variable
• List Functions For A Namespace
• Load A File Into The REPL
• Mapping With An Index
• Open JavaDocs
• Pretty Print The Last Thing
• Quick Clojure Docs
• Reductions
• Set Max Heap Size
• Specify the Directory of a Shell Command
• Splitting On Whitespace
• Swap Two Items in a Vector
• Try A Clojure Project In The REPL
• Type of Anything
• When Overflow Is Desired

CSS

• Add Fab Icons To Your Site With FontAwesome 5
• Animate Smoothly Between Two Background Colors
• Apply Multiple Box Shadows To Single Element
• Apply Styles Based On Dark-Mode Preferences
• Apply Styles To The Last Child Of A Specific Type
• Change The Orientation Of An Image
• Circular Icons With A Massive Border Radius
• Clean Up Repetition With :is() Pseudo-Class
• Conditional Styling For Unsupported CSS Features
• Create A Pulsing Background With CSS Animation
• Define CSS Custom Properties With CSS Variables
• Define HSL Colors With Alpha Values
• Display Responsive iframe Maintaining Aspect Ratio
• Dry Up SCSS With Mixins
• Give Elements The Same Width With Flexbox
• Let Pointer Events Pass Through An Element
• Lighten And Darken With CSS Brightness Filter
• Lighten And Darken With SCSS
• Make A Block Of Text Respect New Lines
• Parameterized SCSS Mixins
• :root Has Higher Specificity Than html
• Style A Background With A Linear Gradient
• Using Maps In SCSS

Deno

• Read In The Contents Of A File

Devops

• Aliasing An Ansible Host
• Allow Cross-Origin Requests To Include Cookies
• Allow HTTPS Through Your UFW Firewall
• Check The Status of All Services
• Check The Syntax Of nginx Files
• Connect To An RDS PostgreSQL Database
• Determine The IP Address Of A Domain
• Path Of The Packets
• Push Non-master Branch To Heroku
• Reload The nginx Configuration
• Resolve The Public IP Of A URL
• Running Out Of inode Space
• SSH Into A Docker Container
• SSL Certificates Can Cover Multiple Domains
• Wipe A Heroku Postgres Database

Elixir

• All Values For A Key In A Keyword List
• Append To A Keyword List
• Assert An Exception Is Raised
• Binary Representation Of A String
• Check For A Substring Match
• Check List Membership
• Comparing DateTime Structs
• Compute Intermediate Values In A With Construct
• Compute md5 Digest Of A String
• Counting Records With Ecto
• Create A Date With The Date Sigil
• Create A List Of Atoms
• Creating A PID
• Creating Indexes With Ecto
• Defining Multiple Clauses In An Anonymous Function
• Determine The Latest Release Of A Hex Package
• Do You Have The Time?
• Do You Have The Time? - Part 2
• Documentation Lookup With Vim And Alchemist
• Dynamically Generating Atoms
• Execute Raw SQL In An Ecto Migration
• Expose Internal Representation
• Include Captures With String.split
• Inspecting The Process Message Queue
• List Functions For A Module
• Listing Files In IEx
• Match On A Map In A With Construct
• Passing Around And Using Modules
• Pattern Matching In Anonymous Functions
• Pipe Into A Case Statement
• Quitting IEx
• Range Into List Using Comprehensions
• Refer To A Module Within Itself
• Referencing Values In IEx's History
• Remove One List From Another
• Replace Duplicates In A Keyword List
• Requiring Keys For Structs
• Reversing A List
• Reversing A List - Part 2
• Root Directory Of A Project
• Round Floats To Integers
• Run ExUnit Tests In A Deterministic Order
• Run The Test At A Specific Line Number
• Same Functions Should Be Grouped Together
• Skip A Specific Test
• String Interpolation With Just About Anything
• Unique Indexes With Ecto
• Updating Values In A Map
• Using When Clauses In A With Construct
• Virtual Fields With Ecto Schemas
• When Things Don't Match The With Statements
• Word Lists For Atoms

Gatsby

• Add JavaScript To Body Of The Document

Git

• Accessing a Lost Commit
• Amend Author Of Previous Commit
• Auto-Squash Those Fixup Commits
• Caching Credentials
• Change The Start Point Of A Branch
• Checking Commit Ancestry
• Checkout Old Version Of A File
• Checkout Previous Branch
• Cherry Pick A Range Of Commits
• Clean Out All Local Branches
• Clean Out Working Copy With Patched Restore
• Clean Up Old Remote Tracking References
• Clone A Repo Just For The Files, Without History
• Clone A Repo Locally From .git
• Configure Global gitignore File
• Configuring The Pager
• Copy A File From Another Branch
• Create A New Branch With Git Switch
• Delete All Untracked Files
• Determine The Hash Id For A Blob
• Diffing With Patience
• Dropping Commits With Git Rebase
• Dry Runs in Git
• Exclude A File From A Diff Output
• Excluding Files Locally
• Find The Date That A File Was Added To The Repo
• Find The Initial Commit
• Get The Name Of The Current Branch
• Get The Short Version Of The Latest Commit
• Grab A Single File From A Stash
• Grep For A Pattern On Another Branch
• Grep Over Commit Messages
• Ignore Changes To A Tracked File
• Ignore Files Specific To Your Workflow
• Include A Message With Your Stashed Changes
• Include Or Exclude Remaining Patch Changes
• Include Some Stats In Your Git Log
• Intent To Add
• Interactively Unstage Changes
• Last Commit A File Appeared In
• List All Files Changed Between Two Branches
• List Branches That Contain A Commit
• List Commits On A Branch
• List Different Commits Between Two Branches
• List Filenames Without The Diffs
• List Just The Files Involved In A Commit
• List Most Git Commands
• List Untracked Files
• List Untracked Files For Scripting
• Move The Latest Commit To A New Branch
• Pick Specific Changes To Stash
• Pulling In Changes During An Interactive Rebase
• Push To A Branch On Another Remote
• Quicker Commit Fixes With The Fixup Flag
• Rebase Commits With An Arbitrary Command
• Reference A Commit Via Commit Message Pattern Matching
• Rename A Remote
• Renaming A Branch
• Resetting A Reset
• Resolve A Merge Conflict From Stash Pop
• Run A Git Command From Outside The Repo
• Set A Custom Pager For A Specific Command
• Show All Commits For A File Beyond Renaming
• Show Changes For Files That Match A Pattern
• Show Changes In The Compose Commit Message View
• Show File Diffs When Viewing Git Log
• Show List Of Most Recently Committed Branches
• Show Only Commits That Touch Specific Lines
• Show The diffstat Summary Of A Commit
• Show The Good And The Bad With Git Bisect
• Show What Is In A Stash
• Single Key Presses in Interactive Mode
• Skip A Bad Commit When Bisecting
• Skip Pre-Commit Hooks
• Staging Changes Within Vim
• Staging Stashes Interactively
• Stash A Single Untracked File
• Stash Everything
• Stashing Only Unstaged Changes
• Stashing Untracked Files
• Switch To A Recent Branch With FZF
• Turn Off The Output Pager For One Command
• Two Kinds Of Dotted Range Notation
• Unstage Changes Wih Git Restore
• Untrack A Directory Of Files Without Deleting
• Untrack A File Without Deleting It
• Update The URL Of A Remote
• Using Commands With A Relative Date Format
• Verbose Commit Message
• Viewing A File On Another Branch
• What Changed?
• What Is The Current Branch?
• Whitespace Warnings

GitHub Actions

• Capture An Output Value For Use In A Later Step
• Reference An Encrypted Secret In An Action

Go

• Access Go Docs Offline
• Build For A Specific OS And Architecture
• Not So Random
• Replace The Current Process With An External Command
• Sleep For A Duration
• Upgrading From An Older Version On Mac

Heroku

• Deploy A Review App To A Different Stack
• Set And Show Heroku Env Variables
• SSH Into Heroku Server Hosting App

HTML

• Adding Alt Text To An Image
• Disable Auto-Completion For A Form Input
• Prevent Search Engines From Indexing A Page
• Render Text As Superscript
• Submit A Form With A Button Outside The Form

HTTP

• What Counts As Cross-Origin With CORS?

Internet

• Add Emoji To GitHub Repository Description
• Enable Keyboard Shortcuts In Gmail
• Exclude Whitespace Changes From GitHub Diffs
• Figure Out Your Public IP Address
• Focus The URL Bar
• Get Random Images From Unsplash
• Search Tweets By Author
• Show All Pivotal Stories With Blockers

JavaScript

• Accessing Arguments To A Function
• Basic Date Formatting Without A Library
• Character Codes from Keyboard Listeners
• Check Classes On A DOM Element
• Check If A Number Is Positive Or Negative
• Check If Something Is An Array
• Check The Password Confirmation With Yup
• Compare The Equality Of Two Date Objects
• Computed Property Names In ES6
• Conditionally Include Pairs In An Object
• Configure Jest To Run A Test Setup File
• Create A Cancelable Promise With PCancelable
• Create An Array Containing 1 To N
• Create An Object With No Properties
• Create Bootstrapped Apps With Yarn
• Create Future And Past Dates From Today
• Custom Type Checking Error Messages With Yup
• Default And Named Exports From The Same Module
• Define A Custom Jest Matcher
• Destructure With Access To Nested Value And Parent Value;
• Destructuring The Rest Of An Array
• Enable ES7 Transforms With react-rails
• Ensure Shell Can Find Global npm Binaries
• Easy Date Comparison With DayJS
• Expand Emojis With The Spread Operator
• Fill An Input With A Ton Of Text
• Find The Version Of An Installed Dependency
• Find Where Yarn Is Installing Binaries
• for...in Iterates Over Object Properties
• Formatting Values With Units For Display
• Freeze An Object, Sorta
• Generate Random Integers
• Get The Location And Size Of An Element
• Get The Response Status From An Axios Error
• Get The Time Zone Of The Client Computer
• Globally Install A Package With Yarn
• Immutable Remove With The Spread Operator
• Initialize A New JavaScript Project With Yarn
• Install The Latest Version Of Node With Nvm
• Interpolate A String Into A Regex
• ISO-8601 Formatted Dates Are Interpreted As UTC
• Link A JavaScript Package Locally
• List Top-Level NPM Dependencies
• Make The Browser Editable With Design Mode
• Matching A Computed Property In Function Args
• Matching Multiple Values In A Switch Statement
• Mock A Function With Return Values Using Jest
• New Dates Can Take Out Of Bounds Values
• Numbers Are Empty
• Object Initialization With Shorthand Property Names
• Obtain Undefined Value With The Void Operator
• Parse A Date From A Timestamp
• Random Cannot Be Seeded
• Reach Into An Object For Nested Data With Get
• Render An Array Of Elements With React 16
• Resolve And Pass Multiple Values From A Then
• Running ES6 Specs With Mocha
• Scoping Variables With A Block Statement
• Sleep For A Bit In Async Code
• Sorting Arrays Of Objects With Lodash
• Splat Arguments To A Function
• Spread The Rest With ES6
• Start Node Process In Specific Timezone
• String Interpolation With Template Literals
• Support Nested Matching In Custom Jest Matchers
• Tell Prettier To Not Format A Statement
• Test Coverage Stats With Jest
• Test Timing-Based Code With Jest Fake Timers
• The Comma Operator
• Throttling A Function Call
• Timing Processes
• Transforming ES6 and JSX With Babel 6
• Truthiness of Integer Arrays
• Turn An HTMLCollection Into An Array
• Turn Off Console Error Messages In A Test
• Waiting On Multiple Promises
• Who Am I: NPM Edition
• Yarn Commands Without The Emojis
• Yup Schemas Are Validated Asynchronously

jq

• Extract A List Of Values

Kitty

• Set The Title Of A Window
• Use The Built-In Emoji Picker

Linux

• Check Ubuntu Version
• Configure Your Server Timezone
• List The Statuses Of All Upstart Jobs
• Show Current System Time And Settings
• Upgrading Ubuntu

Mac

• Access All Screen And Video Capture Options
• Access System Information On OS X
• Access Unsupported Screen Resolutions With RDM
• Clean Up Old Homebrew Files
• Convert An HEIC Image File To JPG
• Default Screenshot Location
• Disable Swipe Navigation For A Specific App
• Display A Message With Alfred
• Find The Process Using A Specific Port
• Gesture For Viewing All Windows Of Current App
• Insert A Non-Breaking Space Character
• List All The Say Voices
• Quickly Type En Dashes And Em Dashes
• Require Additional JS Libraries In Postman
• Resize App Windows With AppleScript
• Resizing Both Corners Of A Window
• Run A Hardware Check
• Run AppleScript Commands Inline In The Terminal
• Set A Window To Its Default Zoom Level
• Specify App When Opening From Command Line
• Use Default Screenshot Shortcuts With CleanShot X
• View All Windows Of The Current App

MongoDB

• Determine The Database Version
• Dump A Remote Database
• Get Size Stats For A Collection
• List Size Stats For All Collections

MySQL

• Display Output In A Vertical Format
• Doing Date Math
• Dump A Database To A File
• List Databases And Tables
• Show Create Statement For A Table
• Show Tables That Match A Pattern
• Show Indexes For A Table

Netlify

• Override The Default Yarn Version

Next.js

• Create Files And Directories For Dynamic Routes
• Define URL Redirects In The Next Config
• Push A Route With A URL Object
• Remove A Query Param From The URL
• Ship Public Assets With A Next.js App

Phoenix

• Bypass Template Rendering
• Check The Installed Version
• Generate New App Without Brunch
• Render A Template To A String
• Serve Static Assets From Custom Directory
• Specifying The Digest Directory
• Specifying The Server Port

PostgreSQL

• A Better Null Display Character
• Add Foreign Key Constraint Without A Full Lock
• Add ON DELETE CASCADE To Foreign Key Constraint
• Adding Composite Uniqueness Constraints
• Aggregate A Column Into An Array
• Assumed Radius Of The Earth
• Auto Expanded Display
• Between Symmetric
• Capitalize All The Words
• Change The Current Directory For psql
• Check If The Local Server Is Running
• Check Table For Any Oprhaned Records
• Checking Inequality
• Checking The Type Of A Value
• Clear The Screen In psql
• Clear The Screen In psql (2)
• Compute Hashes With pgcrypto
• Compute The Levenshtein Distance Of Two Strings
• Compute The md5 Hash Of A String
• Configure The Timezone
• Constructing A Range Of Dates
• Convert A String To A Timestamp
• Count How Many Records There Are Of Each Type
• Count Records By Type
• Count The Number Of Trues In An Aggregate Query
• Create A Composite Primary Key
• Create An Index Without Locking The Table
• Create Database Uses Template1
• Create hstore From Two Arrays
• Create Table Adds A Data Type
• Creating Conditional Constraints
• Creating Custom Types
• Day Of Week By Name For A Date
• Day Of Week For A Date
• Default Schema
• Defining Arrays
• Determine Types Of JSONB Records
• Determining The Age Of Things
• Difference Between Explain And Explain Analyze
• Dump All Databases To A SQL File
• Dump And Restore A Database
• Duplicate A Local Database
• Edit Existing Functions
• Escaping A Quote In A String
• Escaping String Literals With Dollar Quoting
• Export Query Results To A CSV
• Extracting Nested JSON Data
• Find Duplicate Records In Table Without Unique Id
• Find Records That Contain Duplicate Values
• Find Records That Have Multiple Associated Records
• Find The Data Directory
• Find The Location Of Postgres Config Files
• Fizzbuzz With Common Table Expressions
• Force SSL When Making A psql Connection
• Generate A UUID
• Generate Random UUIDs Without An Extension
• Generate Series Of Numbers
• Generating UUIDs With pgcrypto
• Get A Quick Approximate Count Of A Table
• Get The Size Of A Database
• Get The Size Of A Table
• Get The Size Of An Index
• Getting A Slice Of An Array
• Group By The Result Of A Function Call
• Insert A Bunch Of Records With Generate Series
• Insert Just The Defaults
• Install Postgres With uuid-ossp Using asdf
• Integers In Postgres
• Intervals Of Time By Week
• Is It Null Or Not Null?
• Limit Execution Time Of Statements
• List All Columns Of A Specific Type
• List All Rows In A Table
• List All The Databases
• List All Versions Of A Function
• List Available Schemas
• List Connections To A Database
• List Database Objects With Disk Usage
• List Database Users
• List Various Kinds Of Objects
• Lower Is Faster Than ilike
• Max Identifier Length Is 63 Bytes
• pg Prefix Is Reserved For System Schemas
• Prepare, Execute, And Deallocate Statements
• Pretty Print Data Sizes
• Pretty Printing JSONB Rows
• Prevent A Query From Running Too Long
• Print The Query Buffer In psql
• Remove Not Null Constraint From A Column
• Renaming A Sequence
• Renaming A Table
• Restart A Sequence
• Restarting Sequences When Truncating Tables
• Salt And Hash A Password With pgcrypto
• Send A Command To psql
• Set Inclusion With hstore
• Set A Seed For The Random Number Generator
• Set A Statement Timeout Threshold For A Session
• Sets With The Values Command
• Shorthand Absolute Value Operator
• Show All Versions Of An Operator
• Sleeping
• Special Math Operators
• Storing Emails With citext
• String Contains Another String
• Switch Non-Castable Column Type With Using Clause
• Switch The Running Postgres Server Version
• Temporarily Disable Triggers
• Temporary Tables
• Terminating A Connection
• The nullif Function
• Timestamp Functions
• Toggling The Pager In PSQL
• Track psql History Separately Per Database
• Truncate All Rows
• Truncate Tables With Dependents
• Turning Timing On
• Two Ways To Compute Factorial
• Two Ways To Escape A Quote In A String
• Types By Category
• Union All Rows Including Duplicates
• Use A psqlrc File For Common Settings
• Use Argument Indexes
• Use Not Valid To Immediately Enforce A Constraint
• Using Expressions In Indexes
• Using Intervals To Offset Time
• Who Is The Current User
• Word Count for a Column
• Write A Query Result To File

Python

• Access Instance Variables
• Create A Dummy DataFrame In Pandas
• Test A Function With Pytest

Rails

• Add A Check Constraint To A Table
• Add A Foreign Key Reference To A Table
• Add A Reference Column With An Index
• Add ActiveRecord Error Not Tied To Any Attribute
• Add React With Webpacker To A New Rails App
• Add timestamptz Columns With The Migration DSL
• Access Secrets In A Rails 5.2 App
• ActiveRecord Query For This Or That
• Advance The Date
• Allow List Params Anywhere With Strong Params
• All or Nothing Database Transactions
• Assert Two Arrays Have The Same Items With RSpec
• Attach A File With Capybara
• Attribute Getter without the Recursion
• Attribute Was
• Autosave False On ActiveRecord Associations
• Bind Parameters To ActiveRecord SQL Query
• Build A Hash Of Model Attributes
• Capture Development Emails With Mailhog
• Capybara Page Status Code
• Cast Common Boolean-Like Values To Booleans
• Change The Nullability Of A Column
• Change The Time Zone Offset Of A DateTime Object
• Check If ActiveRecord Update Fails
• Check If Any Records Have A Null Value
• Check Specific Attributes On ActiveRecord Array
• Code Statistics For An Application
• Columns With Default Values Are Nil On Create
• Comparing DateTimes Down To Second Precision
• Conditional Class Selectors in Haml
• Convert A Symbol To A Constant
• Count The Number Of Records By Attribute
• Create A Custom Named References Column
• Create A Join Table With The Migration DSL
• Creating Records of Has_One Associations
• Custom Validation Message
• Customize Paths And Helpers For Devise Routes
• Customize The Path Of A Resource Route
• Delete Paranoid Records
• Demodulize A Class Name
• Different Ways To Add A Foreign Key Reference
• Disambiguate Where In A Joined Relation
• Ensure Migrations Use The Latest Schema
• Find Or Create A Record With FactoryBot
• Find Records With Multiple Associated Records
• Force All Users To Sign Out
• Generating And Executing SQL
• Get An Array Of Values From The Database
• Get An Empty ActiveRecord Relation
• Get The Column Names For A Model
• Get The Current Time
• Grab A Random Record From The Database
• Handle Named Arguments In A Rake Task
• Hash Slicing
• Ignore Poltergeist JavaScript Errors
• Include Devise Helpers In Your Controller Tests
• Inspect Previous Changes To ActiveRecord Object
• Link To The Current Page With Query Params
• List All Installable Rails Versions
• List The Enqueued Jobs
• Load Records In Batches With find_each
• Log SQL Queries Executed By ActiveRecord
• Mark A Migration As Irreversible
• Make ActionMailer Synchronous In Test
• Manually Run A Migration From Rails Console
• Mark For Destruction
• Mask An ActiveRecord Attribute
• Merge A Scope Into An ActiveRecord Query
• Migrating Up Down Up
• Order Matters For rescue_from Blocks
• Params Includes Submission Button Info
• Parse Query Params From A URL
• Perform SQL Explain With ActiveRecord
• Polymorphic Path Helpers
• Pretend Generations
• Prevent Writes With A Sandboxed Rails Console
• Query A Single Value From The Database
• Read In Environment-Specific Config Values
• Read-Only Models
• Remove The Default Value On A Column
• Render An Alternative ActionMailer Template
• Render The Response Body In Controller Specs
• Replace An Index With A Unique Index
• Rescue From
• Rescue From With A Separate Method
• Retrieve An Object If It Exists
• Rollback A Specific Migration Out Of Order
• Rounding Numbers With Precision
• Schedule Sidekiq Jobs Out Into The Future
• Secure Passwords With Rails And Bcrypt
• Select A Select By Selector
• Select Value For SQL Counts
• Serialize With fast_jsonapi In A Rails App
• Set A Timestamp Field To The Current Time
• Set default_url_options For Entire Application
• Set Schema Search Path
• Set Statement Timeout For All Postgres Connections
• Set The Default Development Port
• Show Pending Migrations
• Show Rails Models With Pry
• Show Rails Routes With Pry
• Skip Validations When Creating A Record
• Specify New Attributes For #find_or_create_by
• Temporarily Disable strong_params
• Test If An Instance Variable Was Assigned
• Test If deliver_later Is Called For A Mailer
• Test Out URL And Path Helpers In The Console
• Truncate Almost All Tables
• Update Column Versus Update Attribute
• Upgrading Your Manifest For Sprocket's 4
• Verify And Read A Signed Cookie Value
• Where Am I In The Partial Iteration?
• Wipe Out All Precompiled Assets
• Write Reversible Migration To Set Default
• Write Safer Where Clauses With Placeholders

React

• A Component Is Just A Bag Of Data
• Access The Latest Lifecycle Methods In An Old App
• Accessing Env Vars In create-react-app
• Accessing Location Within @reach/router
• Allow md As An Extension With gatsby-mdx
• Alter The Display Name Of A Component
• Building A React App In The Browser
• Check The Type Of A Child Component
• Conditionally Including Event Handler Functions
• Create A Snowpack-Bundled React App
• Create Dynamically Named Custom React Components
• create-react-app Comes With Lodash
• create-react-app Has A Default Test Setup File
• CSS !important Is Not Supported By Inline Styles
• Debug Jest Tests In create-react-app
• Defining State In A Simple Class Component
• Destructure Variables As Props To A Component
• Details Tags Are A Controllable Component
• Dispatch Anywhere With Redux
• Dynamically Add Props To A Child Component
• Dynamically Create HTML Elements
• Enforce Specific Values With PropTypes
• Focus An Input With useRef Hook
• Force A Component To Only Have One Child
• Forcing A Child Remount With The Key Prop
• Formik Connected Components
• Formik's Validation Schema As A Function
• Inactive And Active Component Styles With Radium
• Inline Style Attributes Should Be Camel Cased
• Manage State In A Functional Component
• Mapping Over One Or Many Children
• Mock A Function That A Component Imports
• Navigate With State Via @reach/router
• Pairing A Callback With A useState Hook
• Pass A Function To A useState Updater
• Passing Props Down To React-Router Route
• Prevent reach/router Redirect Error Screen In Dev
• Proxy To An API Server In Development With CRA
• Quickly Search For A Component With React DevTools
• @reach/router Renders To A Div
• Read Only Input Elements
• Rendering Multiple Nodes With Fragments
• Set The Type For A useState Hook
• Specifying Dependencies Of A useEffect Hook
• Spelunking Through Components With Enzyme's Dive
• Sync Your react-router State With Redux
• Test Files In create-react-app
• Test That Element Does Not Render In The Component
• Trigger Effect Only When The Component Mounts
• Update Formik Initial Values When Props Change
• Upgrading To The Latest React In CodeSandbox
• Use A Ref To Autofocus An Input
• Use React 16 With Gatsby
• Use withRouter To Pass Down React-Router History
• Visually Select A React Element For Inspection
• Who Is Your Favorite Child?
• Wrap The Root Of A Gatsby App In A Component

React Native

• Avoid The Notch With SafeAreaView

React Testing Library

• Check That A Component Renders As Null
• findBy* Queries Have Async Built In
• Pretty Print Some DOM To Debug A Test
• Test A Component That Uses React Portals

ReasonML

• Break Out Of A While Loop
• Compile Reason To Native With Dune
• Compile Reason With An OCaml Package Using Dune
• Create A Map Of Strings
• Create A Stream From An Array
• Creating A 2D Array
• Data Structures With Self-Referential Types
• Defining Variants With Constructor Arguments
• Dynamically Create A Printf String Format
• Exhaustive Pattern Matching Of List Variants
• Format The Current File Within Vim
• Generate A Native ReasonML Project With Pesy
• Generate Starter Reason Projects
• Helping The Compiler Help Us With Variants
• Inline Component Styles With Reason React
• Is This A Directory Or A File?
• Making Things Mutable
• Modifying A String With blit_string
• Multi-Argument Functions As Syntactic Sugar
• Pattern Match On Exceptions
• Quickly Bootstrap A React App Using Reason
• Seeding And Generating Random Integers
• Stream A File Line By Line
• String Interpolation With Integers And Sprintf
• String Interpolation With Quoted Strings
• Trying Out ReasonML In CodeSandbox
• Two Ways To Find An Item In A List
• Using Optional Labeled Function Arguments
• Wrapping A Component For Use In JavaScript

RSpec

• Check Specific Arguments To Received Method
• Find Minimal Set Of Tests Causing A Flicker

Ruby

• A Basic Case Statement
• A Shorthand For Rerunning Failed Tests With RSpec
• Add Comments To Regex With Free-Spacing
• Add Linux As A Bundler Platform
• Are They All True?
• Assert About An Object's Attributes With RSpec
• Assoc For Hashes
• Block Comments
• Build HTTP And HTTPS URLs
• Chaining Multiple RSpec Change Matchers
• Check If An Object Includes A Module
• Check Return Status Of Running A Shell Command
• Click On Text With Capybara
• Colorful Output With MiniTest
• Comparing Class Hierarchy Relationships
• Comparing Arrays In RSpec
• Construct A Constant From A String
• Convert A Unix Epoch Timestamp To A Time Object
• Create an Array of Stringed Numbers
• Create a CSV::Table Object
• Create A Hash From An Array Of Arrays
• Create Listing Of All Middleman Pages
• Create Named Structs With Struct.new
• Create Thumbnail Image For A PDF
• Defaulting To Frozen String Literals
• Define A Custom RSpec Matcher
• Define A Method On A Struct
• Destructure The First Item From An Array
• Destructuring Arrays In Blocks
• Disassemble Some Codes
• Double Splat To Merge Hashes
• Edit Previous Parts Of The Pry Buffer History
• Editing Code In Pry
• Encode A String As URL-Safe Base64
• Enumerate A Pairing Of Every Two Sequential Items
• Evaluating One-Off Commands
• Exclude Values From An Array
• Expect A Method To Be Called And Actually Call It
• Extract A Column Of Data From A CSV File
• FactoryGirl Sequences
• Fail
• Find The Min And Max With A Single Call
• Finding The Source of Ruby Methods
• Generate A Signed JWT Token
• Generate Ruby Version And Gemset Files With RVM
• Get Info About Your RubyGems Environment
• Identify Outdated Gems
• If You Detect None
• Iterate With An Offset Index
• Include Extra Context In A Honeybadger Notify
• Ins And Outs Of Pry
• Invoking Rake Tasks Multiple Times
• IRB Has Built-In Benchmarking With Ruby 3
• Jump Out Of A Nested Context With Throw/Catch
• Last Raised Exception In The Call Stack
• Limit Split
• List The Running Ruby Version
• Listing Local Variables
• Map With Index Over An Array
• Mock Method Chain Calls With RSpec
• Mocking Requests With Partial URIs Using Regex
• Named Regex Captures Are Assigned To Variables
• Navigate Back In The Browser With Capybara
• Next And Previous Floats
• Or Operator Precedence
• Override The Initial Sequence Value
• Parallel Bundle Install
• Parse JSON Into An OpenStruct
• Parsing A CSV With Quotes In The Data
• Pass A Block To Count
• Passing Arbitrary Methods As Blocks
• Passing Arguments To A Rake Task
• Pattern Match Values From A Hash
• Percent Notation
• Question Mark Operator
• Rake Only Lists Tasks With Descriptions
• Read The First Line From A File
• Rendering ERB
• Replace The Current Process With An External Command
• Require Entire Gemfile In Pry Session
• Rerun Only Failures With RSpec
• Retry A Block After An Exception
• Returning With Sequel
• rexml Is A Bundled Gem As Of Ruby 3.0.0
• Run An Older Version Of Bundler
• Running A Single MiniTest Example
• Safe Navigation Operator
• Scripting With RVM
• Scroll To Top Of Page With Capybara
• Set RVM Default Ruby
• Show Public Methods With Pry
• Silence The Output Of A Ruby Statement In Pry
• Single And Double Quoted String Notation
• Squeeze Out The Extra Space
• String Interpolation With Instance Variables
• Summing Collections
• Triple Equals: The Case Equality Operator
• Turn Key And Value Arrays Into A Hash
• Turning Any Class Into An Enumerator
• Turning Things Into Hashes
• Uncaught Exceptions In Pry
• undef_method And The Inheritance Hierarchy
• Uninstall Specific Version Of A Ruby Gem
• Unpacking Strings Into Binary
• Up And Down With Integers
• Update The Gemfile Bundled With Version
• Use A Case Statement As A Cond Statement
• Use dotenv In A Non-Rails Project
• Use Tap For Better Test Data Setup
• Using BCrypt To Create And Check Hashed Passwords
• What To Do When You Don't Rescue
• Who Are My Ancestors?
• Wrap Things In An Array, Even Hashes
• Zero Padding

sed

• Apply Multiple Substitutions To The Input
• Equivalence Classes Of Repetition MetaChars
• Extract Value From Command Output With Sed
• Grab All The Method Names Defined In A Ruby File
• Grab The First Line Of A File
• OSX sed Does Regex A Bit Different
• Output Only Lines Involved In A Substitution
• Reference A Capture In The Regex
• Use An Alternative Delimiter In A Substitution

Shell

• Check If The First Argument Is Given
• Format And Print The Current Date And Time

Streaming

• Monitor An Audio Input Device In OBS

Tailwind CSS

• Base Styles For Text Link
• Specify Paths For Purging Unused CSS
• Use Tailwind Typography Prose In Dark Mode

tmux

• Access Past Copy Buffer History
• Adjusting Window Pane Size
• Break Current Pane Out To Separate Window
• Change Base Directory Of Existing Session
• Change The Default Prefix Key
• Create A Named tmux Session
• Create A New Session In A New Server
• Cycle Through Layouts
• Enabling Vi Mode
• Get Mouse Copy/Paste Working In Kitty
• Hiding The Status Bar
• Jumping Between Sessions
• Kill All Your tmux Sessions
• Kill Other Connections To A Session
• Kill The Current Session
• List All Key Bindings
• List Sessions
• Open New Window With A Specific Directory
• Organizing Windows
• Paging Up And Down
• Pane Killer
• Reclaiming The Entire Window
• Remove The Delay On The Escape Key
• Rename The Current Session
• Reset An Option Back To Its Default Value
• Set Session Specific Environment Variables
• Show The Current Value For An Option
• Swap Split Panes
• Switch To A Specific Session And Window
• tmux in your tmux
• Toggle Between Two Common Sessions

TypeScript

• Add Types To An Object Destructuring
• Compiler Checks For Unused Params And Variables
• Re-Export An Imported Type
• Type Narrowing With Similarly Shaped Objects
• Use An Array Check For Type Narrowing
• Zero-Config Environments For Trying Out Types

Unix

• All The Environment Variables
• Cat A File With Line Numbers
• Cat Files With Color Using Bat
• Change Default Shell For A User
• Change To That New Directory
• Check If A Port Is In Use
• Check If Command Is Executable Before Using
• Check The Current Working Directory
• Clear The Screen
• Command Line Length Limitations
• Compare Two Variables In A Bash Script
• Configure cd To Behave Like pushd In Zsh
• Copying File Contents To System Paste Buffer
• Copying Nested Directories With Ditto
• Count The Number Of Matches In A Grep
• Create A File Descriptor with Process Substitution
• Create A Sequence Of Values With A Step
• Curl With Cookies
• Curling For Headers
• Curling With Basic Auth Credentials
• Display All The Terminal Colors
• Display Free Disk Space
• Display The Contents Of A Directory As A Tree
• Do A Dry Run Of An rsync
• Do Not Overwrite Existing Files
• Enable Multi-Select Of Results With fzf
• Exclude A Directory With Find
• Exclude Certain Files From An rsync Run
• Figure Out The Week Of The Year From The Terminal
• File Type Info With File
• Find A File Installed By Brew
• Find Files With fd
• Find Newer Files
• Fix Unlinked Node Binaries With asdf
• Forward Multiple Ports Over SSH
• Generate A SAML Key And Certificate Pair
• Get Matching Filenames As Output From Grep
• Get The Unix Timestamp
• Global Substitution On The Previous Command
• Globbing For All Directories In Zsh
• Globbing For Filenames In Zsh
• Grep For Files Without A Match
• Grep For Files With Multiple Matches
• Grep For Multiple Patterns
• Hexdump A Compiled File
• Ignore The Alias When Running A Command
• Interactively Browse Available Node Versions
• Jump To The Ends Of Your Shell History
• Kill Everything Running On A Certain Port
• Killing A Frozen SSH Session
• Last Argument Of The Last Command
• Less With Style
• List All Users
• List Files Ordered By Modification Date
• List Names Of Files With Matches
• List Of Sessions To A Machine
• List Parent pid With ps
• List Stats For A File
• List The Available JDKs
• List The Stack Of Remembered Directories
• Map A Domain To localhost
• Only Show The Matches
• Open The Current Command In An Editor
• Partial String Matching In Bash Scripts
• PID Of The Current Shell
• Print A Range Of Lines For A File With Bat
• Print Out Files In Reverse
• Provide A Fallback Value For Unset Parameter
• Repeat Yourself
• Saying Yes
• Search Files Specific To A Language
• Search History
• Search Man Page Descriptions
• Securely Remove Files
• Set The asdf Package Version For A Single Shell
• Show A File Preview When Searching With FZF
• Show Disk Usage For The Current Directory
• Show The Size Of Everything In A Directory
• Skip Paging If Output Fits On Screen With Less
• SSH Escape Sequences
• SSH With Port Forwarding
• Specify The Language For A File With Bat
• Sort In Numerical Order
• Switch Versions of a Brew Formula
• Touch Access And Modify Times Individually
• Undo Some Command Line Editing
• Update Package Versions Known By asdf Plugin
• Use fzf To Change Directories
• Use Regex Pattern Matching With Grep
• View A Web Page In The Terminal
• Watch The Difference
• Watch This Run Repeatedly
• Where Are The Binaries?

Vercel

• Add Web Server Layer Redirects
• Deploy An App Without Pushing An Empty Commit
• Naming Of The Vercel Config File
• Share Development Environment Variables Via CLI

Vim

• Aborting Git Commits And Rebases
• Absolute And Relative Line Numbers
• Add A File Without Loading It
• Add Custom Dictionary Words
• All The Ways To Write And Quit In Vim
• Allow Neovim To Copy/Paste With System Clipboard
• Almost The End Of The Line
• Alternate Files With vim-rails
• Always Keep The Gutter Open
• Amend Commits With Fugitive
• Backspace Options
• Beginning And End Of Previous Change
• The Black Hole Register
• Blank Lines Above And Below
• Breaking The Undo Sequence
• Buffer Time Travel
• Build And Install A Go Program
• Case-Aware Substitution With vim-abolish
• Case-Insensitive Substitution
• Center The Cursor
• Check For An Executable
• Check Your Current Color Scheme
• Clear Out The Jump List
• Close All Other Splits
• Close All Other Windows
• Close the Current Buffer
• Coerce The Current Filetype
• Coercing Casing With vim-abolish
• Configure FZF To Use fd For File Finding
• Count the Number of Matches
• Create A New Directory In netrw
• Create A New File In A New Directory
• Creating Non-Existent Directories
• Default netrw To Tree Liststyle
• Delete Every Other Line
• Delete Lines That Match A Pattern
• Delete To The End Of The Line
• Deleting Buffers In BufExplorer
• Deleting Directories Of Files From netrw
• Detect If You Are On A Mac
• Difference Between :wq and :x
• Display Word Count Stats
• Edges Of The Selection
• Edit A File At A Specific Line Number
• Edit A File Starting On The Last Line
• End Of The Word
• Escaping Terminal-Mode In An Nvim Terminal
• Filter Lines Through An External Program
• Fix The Spelling Of A Word
• Fold A Visual Selection And Expand It Back
• For When That Escape Key Is Hard To Reach
• Format Long Lines To Text Width
• From Ruby Variables To JavaScript Variables
• Generate and Edit Rails Migration
• Get The pid Of The Session
• Go Back To The Previous Window
• Go To File With Line Number
• Grepping Through The Vim Help Files
• Head of File Name
• Help For Non-Normal Mode Features
• Highlighting Search Matches
• Horizontal to Vertical and Back Again
• Increment All The Numbers
• Incremental Searching
• Interact With The Alternate File
• Interactive Buffer List
• Joining Lines Together
• Jump Back To The Latest Jump Position
• Jump Between And Stage Git Hunks With Fugitive
• Jump To Matching Pair
• Jump To The Next Misspelling
• List All Buffers
• List Of Plugins
• Load A Directory Of Files Into The Buffer List
• Make Directories For The Current File
• Marks Across Vim Sessions
• Match The Beginning And End Of Words
• Moving To A Specific Line
• Navigate To The Nth Column On A Line
• Navigating By Blank Lines
• NETRW Listing Styles
• Next Modified Buffer
• Normal Node Binding To Just Quit
• Open A Tag In A Split Window
• Open an Unnamed Buffer
• Open FZF Result In A Split
• Open Routes File With vim-rails
• Open The Directory Of The Current File
• Open The Fugitive Git Summary Window
• Open The Gemfile
• Open The Latest Rails Migration
• Open The Selected Lines In GitHub With Gbrowse
• Open Vim To A Tag Definition
• Opening a URL
• Opening Man Pages In Vim
• Paste A Register From Insert Mode
• Preventing Typos with Abbreviations
• Previous Buffer
• Previous Visual Selection
• Print The Relative Path Of The Current File
• Print Version Information
• Quick File Info
• Quick Man Pages
• Quick Quickfix List Navigation
• Quickly Fix A Misspelled Word
• Quickly Switch To A Buffer By Number
• Quit When There Is An Argument List
• Re-indenting Your Code
• Read In The Contents Of A Rails File
• Rename A File Through netrw
• Rename Current File
• Repeat The Previous Change
• Repeating Characters
• Replace A Character
• Reset Target tslime Pane
• Reverse A Group Of Lines
• Rotate Everything By 13 Letters
• Rotate The Orientation Of Split Windows
• Running Bundle With vim-bundler
• Scrolling Relative to the Cursor
• Search Backward Through A File
• Searching For Hex Digits
• Select Several Results From An FZF Search
• Set End Of Line Markers
• Set Your Color Scheme
• Set Up Vim-Plug With Neovim
• Setting Filetype With Modelines
• Show All Syntax Highlighting Rules
• Show Matching Entries For Help
• Specify The Line Height Of The Quick Fix Window
• Split Different
• Split The Current Window
• Splitting For New Files
• Source Original vimrc When Using Neovim
• Swap Occurrences Of Two Words
• Swapping Split Windows
• Tabs To Spaces
• The Vim Info File
• Toggle Absolute And Relative Paths In BufExplorer
• Toggling Syntax Highlighting
• Turning Off Search Highlighting
• Unloading A Buffer
• Use Active Window With BufExplorer
• Use The Terminal Inside A Vim Session
• Using vim-surround With A Visual Selection
• Verbose Commits With Fugitive
• View Commit History of a File
• View The Current File In GitHub
• Viewing Man Pages with man.vim
• Vim Without The Extras
• What Is On The Runtime Path?
• Whole Line Auto-Completion
• Wrap With Some Room

VSCode

• Add The VSCode CLI To Your Path
• Advance Through Search Results
• Enable Breadcrumbs For Version 1.26 Release
• Open An Integrated Terminal Window
• Toggle Between Terminals

Webpack

• Better Module Imports With Aliases
• Debugging With Full Source Maps
• Run ESLint As A Preloader
• Specify Port Of CRA's Webpack Dev Server
• Use A Specific Config File

Workflow

• Change Window Name In iTerm
• Convert An ePub Document To PDF On Mac
• Create A Public URL For A Local Server
• Enable Dev Tools For Safari
• Forward Stripe Events To Local Server
• Get Your Public IP Address
• Import A Github Project Into CodeSandbox
• Interactively Kill A Process With fkill
• Open Slack's Keyboard Shortcuts Reference Panel
• Prune The Excess From node_modules
• Rotate An Image To Be Oriented Upright
• Set Recurring Reminders In Slack
• Toggle Between Stories In Storybook
• Update asdf Plugins With Latest Package Versions
• View The PR For The Current GitHub Branch

XState

• Always Use Inline Functions With Assign
• Custom Jest Matcher For XState Machine States
• Define Event That Does Internal Self Transition
• Events Stop Propagating Once Handled
• Inline Actions vs Actions In Machine Options
• Make Immediate And Delayed Transitions
• Simple States And Composite States
• Start A Machine In A Specific State
• Use An XState Machine With React

YAML

• Create Multi-Line Strings Without The Line Breaks
• YAML Is A Superset Of JSON

Usage

The .vimrc file for this project contains a function CountTILs that can be invoked with <leader>c. This will do a substitution count of the current number of TILs and display the result in the command tray.

About

I shamelessly stole this idea from thoughtbot/til.

Other TIL Collections

• Today I Learned by Hashrocket
• jwworth/til
• thoughtbot/til

License

© 2015-2021 Josh Branchaud

This repository is licensed under the MIT license. See LICENSE for details.