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javascript/snippets/pull-at-index.md

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+---
+title: Pull values from array at index
+type: snippet
+tags: [array]
+cover: bug
+dateModified: 2020-10-22T20:24:04+03:00
+---
+
+Mutates the original array to filter out the values at the specified indexes.
+Returns the removed elements.
+
+- Use `Array.prototype.filter()` and `Array.prototype.includes()` to pull out the values that are not needed.
+- Set `Array.prototype.length` to mutate the passed in an array by resetting its length to `0`.
+- Use `Array.prototype.push()` to re-populate it with only the pulled values.
+- Use `Array.prototype.push()` to keep track of pulled values.
+
+```js
+const pullAtIndex = (arr, pullArr) => {
+  let removed = [];
+  let pulled = arr
+    .map((v, i) => (pullArr.includes(i) ? removed.push(v) : v))
+    .filter((v, i) => !pullArr.includes(i));
+  arr.length = 0;
+  pulled.forEach(v => arr.push(v));
+  return removed;
+};
+```
+
+```js
+let myArray = ['a', 'b', 'c', 'd'];
+let pulled = pullAtIndex(myArray, [1, 3]);
+// myArray = [ 'a', 'c' ] , pulled = [ 'b', 'd' ]
+```