38 lines
1.1 KiB
Markdown
38 lines
1.1 KiB
Markdown
---
|
|
title: Initialize array until
|
|
type: snippet
|
|
language: javascript
|
|
tags: [array]
|
|
author: chalarangelo
|
|
cover: neon-desk-2
|
|
dateModified: 2023-06-22T05:00:00-04:00
|
|
---
|
|
|
|
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.
|
|
|
|
```js
|
|
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;
|
|
};
|
|
```
|
|
|
|
```js
|
|
initializeArrayUntil(
|
|
(i, val) => val > 10,
|
|
(i, val, arr) => (i <= 1 ? 1 : val + arr[i - 2])
|
|
); // [1, 1, 2, 3, 5, 8, 13]
|
|
```
|