如何在字符串的指定位置插入新的字符

Question

比如"aaa_bbb" 在_后面插入"ccc_"新的字符串就是"aaa_bbb_ccc"

Answer 1

难道不是"aaa_ccc_bbb"吗
可以重写个原型方法

String.prototype.splice = function(start, newStr) {
    return this.slice(0, start) + newStr + this.slice(start);
};
var index = 'aaa_bbb'.indexOf('_'),
    str = 'aaa_bbb'.splice(index+1, 'ccc_');

Answer 2

你这个问的没懂

var str = 'aaa_bbb';
var reg = /_/g;
var insertStr = "ccc_"
console.log(str.replace(reg,"_"+insertStr))//aaa_ccc_bbb

Answer 3

            var a = "aaa_bbb"
            function insert(str,flg,sn){
                var start = str.substr(0,sn);
                var end = str.substr(sn,str.length);
                  var newstr = start+flg+end;
                return newstr;
            }
            console.log(insert(a,"ccc",a.length));

Answer 4

function addStr(oldStr,addItem,afterWhich){
    var strArr = oldStr.split('');
    strArr.splice(oldStr.indexOf(afterWhich)+1,0,addItem);
    return strArr.join('');
}

//调用函数
addStr('aaa_bbb','ccc_','_')    //"aaa_ccc_bbb"