Generate permutations of JavaScript array
This function, perm(xs), returns all the permutations of a given array:
function perm(xs) { let ret = []; for (let i = 0; i < xs.length; i = i + 1) { let rest = perm(xs.slice(0, i).concat(xs.slice(i + 1))); if(!rest.length) { ret.push([xs[i]]) } else { for(let j = 0; j < rest.length; j = j + 1) { ret.push([xs[i]].concat(rest[j])) } } } return ret;}console.log(perm([1,2,3]).join("\n"));
Using Heap's method (you can find it in this paper which your Wikipedia article links to), you can generate all permutations of N elements with runtime complexity in O(N!) and space complexity in O(N). This algorithm is based on swapping elements. AFAIK this is as fast as it gets, there is no faster method to calculate all permutations.
For an implementation and examples, please have a look at my recent answer at the related question "permutations in javascript".
It is just for fun - my recursive solve in one string
const perm = a => a.length ? a.reduce((r, v, i) => [ ...r, ...perm([ ...a.slice(0, i), ...a.slice(i + 1) ]).map(x => [ v, ...x ])], []) : [[]]