How to determine if a string contains a sequence of repeated letters

Question

Using JavaScript, I need to check if a given string contains a sequence of repeated letters, like this:

\"aaaaa\"

How can I do t

Answer 1

function check(str) {
    var tmp = {};
    for(var i = str.length-1; i >= 0; i--) {
        var c = str.charAt(i);
        if(c in tmp) {
            tmp[c] += 1;
        }
        else {
            tmp[c] = 1;
        }
    }
    var result = {};
    for(c in tmp) {
        if(tmp.hasOwnProperty(c)) {
            if(tmp[c] > 1){
                result[c] = tmp[c];
            }
        }
    }
    return result;
}

then you can check the result to get the repeated chars and their frequency. if result is empty, there is no repeating there.