SOURCE

var aQuery = function(selector, context) {
       return  aQuery.prototype.init();
}
aQuery.prototype = {
    init:function(){
       
        return this;
    },
    name:function(){console.log('name')},
    age:function(){console.log('age')}
}
var it = aQuery()
console.log(it ==  aQuery.prototype)
it.name();
//this指向的是aQuery.prototype。


var aQuery2 = function(selector, context) {
       return  aQuery2.prototype.init();
}
aQuery2.prototype = {
    init: function() {
        this.age = 18
        return this;
    },
    name: function() {},
    age: 20
}

console.log(aQuery2().age)  //18
//this指向的是aQuery.prototype。所以不是实例化。

var aQuery3 = function(selector, context) {
       return  new aQuery3.prototype.init();
}
aQuery3.prototype = {
    init: function() {
        this.age = 18
        return this;
    },
    name: function() {},
    age: 20
}

//Uncaught TypeError: Object [object Object] has no method 'name' 
//this指向new aQuery3.prototype.init生成的实例化，如果没有则找init的原型，而不是aQuery3.prototype。
//console.log(aQuery3().name())


var aQuery4 = function(selector, context) {
       return  new aQuery4.prototype.init();
}
aQuery4.prototype = {
    init: function() {
        //console.log("this.init");
        return this;
    },
    name: function() {
       // console.log("this.age");
        return this.age
    },
    age: 20
}

aQuery4.prototype.init.prototype = aQuery4.prototype;

console.log(aQuery4().name()) //20
console.log(aQuery4.prototype.name());