字符串操作

统计字符串出现的次数

    var ary = "aaaabbbccccdDDDDdfgh";
    var obj = {};
    var i = 0;
    ary1 = ary.toLocaleLowerCase(); //将字符串转为小写
    for(i = 0; i < ary1.length; i ++) {
        var key = ary1[i];
        if (obj[key]) {
            obj[key] ++;
        } else {
            obj[key] = 1;
        }
    }
    for(key in obj) {
        document.write(key + "这个字母出现了" + obj[key] + "次" + "
")
    }
    let num = 0;
    let char = "";
    for(var val in obj) {
        if (obj[val] > num) {
            num = obj[val];
            char = val
        }
    }
    document.write("出现次数最多的是：" + char + "出现了：" + num + "次")

计算字符串的长度 假设：一个英文字符占用一个字节，一个中文字符占用两个字节

      function getBytes(str) {
        var len = str.length;
        var bytes = len;
        for(var i = 0; i< bytes; i++) {
            if(str.charCodeAt(i) > 255) bytes ++
        }
        return bytes;
    }
    console.log(getBytes("你好，asd"))