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

/**
 * @fileoverview  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