JS: Range Function for Array 📜

A Simple Range Function

/* a simple range function */
console.log(Array.from((Array(4)).keys()));
/* [ 0, 1, 2, 3 ] */

xah_range

This is the best function for generating an array. Most efficient and fastest, functional style, and without hack.

/*
xah_range(min, max) → return a array from min to max, inclusive.
xah_range(min, max, step) → in increment of step.

If step is not integer, then max may not be included.

Any min, max, step can be negative. If min ≻ max, step must be negative.

http://xahlee.info/js/js_range_array.html
Version: 2019-10-31
*/

const xah_range = (min, max, step = 1) => (Array(Math.floor((max - min) / step) + 1).fill(min).map((x, i) => (x + i * step)));

// s------------------------------

// test

console.log(xah_range(0, 5));
// [ 0, 1, 2, 3, 4, 5 ]

console.log(xah_range(3, 7));
// [ 3, 4, 5, 6, 7 ]

console.log(xah_range(0, 10, 2));
// [ 0, 2, 4, 6, 8, 10 ]

console.log(xah_range(0, 10, 3));
// [ 0, 3, 6, 9 ]

console.log(xah_range(4, -4, -2));
// [ 4, 2, 0, -2, -4 ]