@extra-array/permutations/index.mjs

Lists all possible permutations.

function concat$(x, ...ys) {
    for (var y of ys)
        x.push(...y);
    return x;
}
function splice(x, i, n = x.length - i, ...vs) {
    return concat$(x.slice(0, i), vs, x.slice(i + n));
}
function* permutationsOf(x, n) {
    var X = x.length;
    if (X === 0 || n === 0) {
        yield [];
        return;
    }
    for (var i = 0; i < X; i++) {
        var y = splice(x, i, 1);
        for (var p of permutationsOf(y, n - 1))
            yield [x[i], ...p];
    }
}
function* permutations(x, n = -1) {
    var X = x.length;
    if (n > X)
        return;
    for (var i = n < 0 ? 0 : n, I = n < 0 ? X : n; i <= I; i++)
        yield* permutationsOf(x, i);
}
export { permutations as default };