//可替换特殊符号$等，但无法忽略大小写的函数String.prototype.replaceStr = function (s1, s2) {    this.str = this;    if (s1.length == 0) return this.str;    var idx = this.str.indexOf(s1);    while (idx > -1) {        this.str = this.str.substring(0, idx) + s2 + this.str.substr(idx + s1.length);        idx = this.str.indexOf(s1);    }    return this.str;}