Does JavaScript have a method like "range()" to generate a range within the supplied bounds?

Question

In PHP, you can do...

range(1, 3); // Array(1, 2, 3) range("A", "C"); // Array("A", "B", "C") 

That is, there is a function that lets you get a range of numbers or characters by passing the upper and lower bounds.

Is there anything built-in to JavaScript natively for this? If not, how would I implement it?

Answer 1

Numbers

[...Array(5).keys()];  => [0, 1, 2, 3, 4] 

Character iteration

String.fromCharCode(...[...Array('D'.charCodeAt(0) - 'A'.charCodeAt(0) + 1).keys()].map(i => i + 'A'.charCodeAt(0)));  => "ABCD" 

Iteration

for (const x of Array(5).keys()) {   console.log(x, String.fromCharCode('A'.charCodeAt(0) + x)); }  => 0,"A" 1,"B" 2,"C" 3,"D" 4,"E" 

As functions

function range(size, startAt = 0) {     return [...Array(size).keys()].map(i => i + startAt); }  function characterRange(startChar, endChar) {     return String.fromCharCode(...range(endChar.charCodeAt(0) -             startChar.charCodeAt(0), startChar.charCodeAt(0))) } 

As typed functions

function range(size:number, startAt:number = 0):ReadonlyArray<number> {     return [...Array(size).keys()].map(i => i + startAt); }  function characterRange(startChar:string, endChar:string):ReadonlyArray<string> {     return String.fromCharCode(...range(endChar.charCodeAt(0) -             startChar.charCodeAt(0), startChar.charCodeAt(0))) } 

lodash.js _.range() function

_.range(10);  => [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] _.range(1, 11);  => [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] _.range(0, 30, 5);  => [0, 5, 10, 15, 20, 25] _.range(0, -10, -1);  => [0, -1, -2, -3, -4, -5, -6, -7, -8, -9] String.fromCharCode(..._.range('A'.charCodeAt(0), 'D'.charCodeAt(0) + 1));  => "ABCD" 

Old non es6 browsers without a library:

Array.apply(null, Array(5)).map(function (_, i) {return i;});  => [0, 1, 2, 3, 4] 

console.log([...Array(5).keys()]);

(ES6 credit to nils petersohn and other commenters)