Initialize array until

JavaScript, Array · Jun 22, 2023

Initializes and fills an array with values generated by a function, until a condition is met.

  • Create an empty array, arr, an index variable i and an element el.
  • Use a do...while loop to add elements to the array, using the mapFn function, until the conditionFn function returns true for the given index i and element el.
  • The condition function, conditionFn, takes three arguments: the current index, the previous element and the array itself.
  • The mapping function, mapFn, takes three arguments: the current index, the current element and the array itself.
const initializeArrayUntil = (conditionFn, mapFn) => {
  const arr = [];
  let i = 0;
  let el = undefined;
  do {
    el = mapFn(i, el, arr);
  } while (!conditionFn(i, el, arr));
  return arr;
  (i, val) => val > 10,
  (i, val, arr) => (i <= 1 ? 1 : val + arr[i - 2])
); // [1, 1, 2, 3, 5, 8, 13]

Written by Angelos Chalaris

I'm Angelos Chalaris, a JavaScript software engineer, based in Athens, Greece. The best snippets from my coding adventures are published here to help others learn to code.

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