Pull values from array at index

JavaScript, Array · Oct 22, 2020

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' ]

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