Add Fill An Input With A Ton Of Text as a javascript til

README.md

@@ -10,7 +10,7 @@ smart people at [Hashrocket](http://hashrocket.com/).
 For a steady stream of TILs from a variety of rocketeers, checkout
 [til.hashrocket.com](https://til.hashrocket.com/).
 
-_594 TILs and counting..._
+_595 TILs and counting..._
 
 ---
 
@@ -222,6 +222,7 @@ _594 TILs and counting..._
 - [Destructuring The Rest Of An Array](javascript/destructuring-the-rest-of-an-array.md)
 - [Enable ES7 Transforms With react-rails](javascript/enable-es7-transforms-with-react-rails.md)
 - [Expand Emojis With The Spread Operator](javascript/expand-emojis-with-the-spread-operator.md)
+- [Fill An Input With A Ton Of Text](javascript/fill-an-input-with-a-ton-of-text.md)
 - [Freeze An Object, Sorta](javascript/freeze-an-object-sorta.md)
 - [Globally Install A Package With Yarn](javascript/globally-install-a-package-with-yarn.md)
 - [Immutable Remove With The Spread Operator](javascript/immutable-remove-with-the-spread-operator.md)

javascript/fill-an-input-with-a-ton-of-text.md

@@ -0,0 +1,31 @@
+# Fill An Input With A Ton Of Text
+
+I needed to test out a form validation for an input that should render an
+error when the length of the context exceeds 10,000 characters. Two small
+tricks make this easy.
+
+First, you can target any DOM element via the Chrome dev tools by selecting
+it and then referencing it via the `$0` magic variable. [More details
+here](https://developers.google.com/web/updates/2015/05/the-currently-selected-dom-node).
+
+```javascript
+> $0
+<input>...</input>
+```
+
+Second, you can quickly and precisely generate a very long string with the
+`repeat` function.
+
+```javascript
+> "a".repeat(10000)
+"aaaaaaaaaaaaaaaaaaaaaaa..."
+```
+
+Combine these two tricks in the browser to fill the input with a ton of
+text:
+
+```javascript
+> $0.value = "a".repeat(10000)
+```
+
+h/t Dillon Hafer