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 variablei
and an elementel
. - Use a
do...while
loop to add elements to the array, using themapFn
function, until theconditionFn
function returnstrue
for the given indexi
and elementel
. - 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); arr.push(el); i++; } while (!conditionFn(i, el, arr)); return arr; }; initializeArrayUntil( (i, val) => val > 10, (i, val, arr) => (i <= 1 ? 1 : val + arr[i - 2]) ); // [1, 1, 2, 3, 5, 8, 13]