var data = {

        "username" : "zhangsan",

        "password" : "12345690",

        "code" : "abcd"

    };

    var validate = {

        rules : {},

        config : {},

        msg : [],

        check : function(data){

            var k, rule, config, checker;

            rule = this.rules;

            config = this.config;

            this.msg.length = 0;

            for(k in data){

                if(data.hasOwnProperty(k)){

                    if(!rule[k]){

                        throw new Error("validate.check error, error type: " + k + " not exist");

                    }

                    checker = this.rules[k];

                    if(!checker.validate(data[k])){

                        this.msg.push(checker.msg);

                    }

                }

            }

        }

    };

    validate.rules.username = {

        validate : function(username){

            return username.length > 7;

        },

        msg : "用户名有误"

    };

    validate.rules.password = {

        validate : function(password){

            return password.length > 7

        },

        msg : "密码挂了"

    };

    validate.rules.code = {

        validate : function(code){

            return code === "abcdef";

        },

        msg : "验证码不对"

    };

    validate.check(data);

    if(validate.msg.length){

        console.log(validate.msg.join("\n"));

    }