number-of-cases-iterative.js

function* numberOfCases(...args) {
    const stack = [[[], args]];
    while (stack.length) {
        const target = stack.shift();
        if (target) {
            const [result, rest] = target;
            for (let i = 0; i < rest.length; i++) {
                let r;
                yield r = [...result, rest[i]];
                stack.push([r, rest.filter((_, index) => index !== i)]);
            }
        }
    }
}
iter = numberOfCases(...'12345'.split(''));
[...iter];