var str = "123456654123789999999879999"
    findMostAppearNum(str);

    function findMostAppearNum(str) {
        str = str.split(‘‘).sort().join(‘‘)
        var re = /(\w)\1+/g;
        var value = http://www.mamicode.com/‘‘;"共出现了："+count+"次")
    }


    var str1 = "a a b a b e";
    var str2 = "123456654123789999999879999"
    console.log(removeDup(str1));
    console.log(removeDup(str2));

    function removeDup(str) {
        var arr =  str.trim().split("").sort();
        var len = arr.length - 1;
        for (var i = len; i > 0; i--) {
            if (arr[i] == arr[i - 1]) {
                arr.splice(i, 1); // 后面和前面的一样删除后面的，如此反复
            }
        }
        return arr
    }