30-seconds-of-code/snippets/js/s/initialize-mapped-array.md

title, type, language, tags, author, cover, dateModified

title	type	language	tags	author	cover	dateModified
Initialize mapped array	snippet	javascript	array	chalarangelo	yellow-shoes	2023-06-13T05:00:00-04:00

Initializes and fills an array with the specified values, using a mapping function.

• Use the Array() constructor to create an array of the desired length.
• Use Array.prototype.fill() to fill it with null values.
• Use Array.prototype.map() to fill it with the desired values, using the provided function, mapFn.
• Omit the second argument, mapFn, to map each element to its index.

const initializeMappedArray = (n, mapFn = (_, i) => i) =>
  Array(n).fill(null).map(mapFn);

initializeMappedArray(5); // [0, 1, 2, 3, 4]
initializeMappedArray(5, i => `item ${i + 1}`);
// ['item 1', 'item 2', 'item 3', 'item 4', 'item 5']