Pull values from array at index

OSCC · 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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