Permutações

permuta.js

var chars = "AEIO",
    iterations = 3,
    output = [];

function iterate(given, iterationsLeft){
    var i, len = chars.length;
    for(i = 0; i < len; i++) {
        if(given.length < iterations-1) {
            iterate(given+chars[i], iterationsLeft-1);
        } else {
            output.push(given+chars[i]);
        }
    }
}
iterate("", iterations);
console.log(output);
console.log(output.length);