Add Extract A List Of Values as a jq til

README.md

@@ -9,7 +9,7 @@ and pairing with smart people at Hashrocket.
 
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-_974 TILs and counting..._
+_975 TILs and counting..._
 
 ---
 
@@ -28,6 +28,7 @@ _974 TILs and counting..._
 * [HTML](#html)
 * [Internet](#internet)
 * [JavaScript](#javascript)
+* [jq](#jq)
 * [Linux](#linux)
 * [Mac](#mac)
 * [MongoDB](#mongodb)
@@ -384,6 +385,10 @@ _974 TILs and counting..._
 - [Yarn Commands Without The Emojis](javascript/yarn-commands-without-the-emojis.md)
 - [Yup Schemas Are Validated Asynchronously](javascript/yup-schemas-are-validated-asynchronously.md)
 
+### jq
+
+- [Extract A List Of Values](jq/extract-a-list-of-values.md)
+
 ### Linux
 
 - [Check Ubuntu Version](linux/check-ubuntu-version.md)

jq/extract-a-list-of-values.md

@@ -0,0 +1,49 @@
+# Extract A List Of Values
+
+[`jq`](https://stedolan.github.io/jq/) can be used to extract a list of values
+from an array in a JSON file.
+
+Consider the following JSON:
+
+```json
+{
+  "items": [
+    { "id": 1, "name": "Liz Lemon" },
+    { "id": 2, "name": "Pete Hornberger" },
+    { "id": 3, "name": "Tracy Jordan" },
+    { "id": 4, "name": "Jenna Maroney" }
+  ]
+}
+```
+
+First, you need to specify the selector path to the list. One it's own that
+will grab the list.
+
+```bash
+$ jq '.items' data.json
+[
+  {
+    "id": 1,
+    "name": "Liz Lemon"
+  },
+  ...
+]
+```
+
+Then you need to use brackets to interact with the list. `.items[0]` and
+`.items[1]` would grab the first and second item in the list, respectively.
+Leaving the brackets empty (`.items[]`) tells `jq` that you want to interact
+with each item in the list.
+
+Then tack on a selector for what you want out of each item.
+
+```bash
+$ jq '.items[].name' data.json
+"Liz Lemon"
+"Pete Hornberger"
+"Tracy Jordan"
+"Jenna Maroney"
+```
+
+This grabs the name from each of the objects within the _items_ array. The
+results are printed to stdout.