Generate sequences of a string

sequence.js

function sequence(str, n) {
    var chars = str.split("");
    n = n || str.length;
    var result = [""];
    for (var i=0;i<n;i++) {
        var newResult = [];
        chars.forEach(function(char){
            result.forEach(function(item) {
                newResult.push(char+item);
            });
        });
        result = newResult;
    }
    return result;
}
sequence("abcdef")
sequence("abcdefghij", 5);