前端笔试题：为字符串实现一个render方法，实现下面的变量替换功能

var greeting = 'my name is $(name),age $(age)';var result = greeting.render({name:'XiaoMing',age:11});console.log(result); //参考答案：

    String.prototype.render = function(option){        var s = this,     reg;        Object.keys(option).forEach(function(k){ reg = new RegExp("\$\("+k+"\)","g"); s = s.replace(reg,option[k])        });        return s    };    var greeting = 'my name is $(name),age $(age)';    var result = greeting.render({name:'XiaoMing',age:11});    console.log(result); // my name is XiaoMing,age 11