30-seconds-of-code/snippets/pullAtIndex.md

title, tags

title	tags
pullAtIndex	array,advanced

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.

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;
};

let myArray = ['a', 'b', 'c', 'd'];
let pulled = pullAtIndex(myArray, [1, 3]);
// myArray = [ 'a', 'c' ] , pulled = [ 'b', 'd' ]