JS中的字符串

//字符串常用属性
    var str = "ancdfrgb";
    document.write(str.length + "<br>");//计算字符串的长度
    document.write(str.charAt(3) + "<br>");//输出指定的字符,超出字符串则输出空
    document.write(str.concat("hhjkk", "kkkk") + "<br>");//字符串拼接
    document.write(str.indexOf("c") + "<br>");//返回字符所在的长度数
    var gg = "jjkkii";
    if (gg.indexOf("jj") == 0) {//替换字符串
        gg = gg.replace("jj", "bb");
    } else {
        document.write("不存在！");
    }
    document.write(gg);
    var str1 = "gopisigvsgvbksefh,alevnaknval";
    document.write(str1.slice(5, 10));//输出指定区域的字符串
    var str2 = "a,c,v,f,h,t,u,r";
    document.write(str2 + "<br>");
    var arr1 = str2.split(",");//切割字符串，并组成一个分组
    for (var i = 0; i < arr1.length; i++) {
        document.write(arr1[i]);}
        
        var str5 = "jjjjjkkkfsvxlvmslvmsv";
        var str2 = str5.substr(5);//从第五个开始输出后面的所有数
        var str3 = str5.substr(5, 5);//从后往前输出指定区域输出字符串
        var str4 = str5.substring(5, 5);//从前往后输出指定区域输出字符串
        document.write(str2 + "<br>");
        document.write(str4 + "<br>");
        document.write(str3);