Is there any pre-built method for finding all permutations of a given string in JavaScript?

//string permutation

function permutation(start, string) {

    //base case
    if ( string.length == 1 ) {
        return [ start + string ];
    } else {

        var returnResult = [];
        for (var i=0; i < string.length; i++) {
            var result = permutation (string[i], string.substr(0, i) + string.substr(i+1));
            for (var j=0; j<result.length; j++) {
                returnResult.push(start + result[j]);
            }
        }

        return returnResult;
    }
}

permutation(”,’123′) will return

[“123”, “132”, “213”, “231”, “312”, “321”]