Javascript 通过本地引用传递回调

Question

可以在这个 JSFiddle 上看到一个例子

我正在创建一个实例，更改该实例的一个函数，然后在该实例的另一个函数中调用该函数。我在更新函数中访问局部变量和实例变量时遇到困难。

代码

var MyObj = function (name) {
    var that = this;
    MyObj.myObjs = (MyObj.myObjs || []),
    this.objName = name,
    this.objIdx = MyObj.myObjs.length;
    MyObj.myObjs.push(this.objName);

    this.doOnSetName = function () {};

    this.setName = function (name) {
        that.doOnNameSet();
        that.objName = name;
        MyObj.myObjs[that.objIdx] = name;
    }
}

var obj1 = new MyObj("obj1");
//obj1.doOnNameSet = function() { alert("objName: "+this.objName) };
//obj1.setName("obj1");

var obj2 = new MyObj("obj2");
obj2.doOnNameSet = function () {
    $("#console").append("Old objName: " + this.name
                         + "<br />New objName: " + name + "<br />")
};
obj2.setName("obj2 - changed");

$("#console ").append("Objects: <br />*" + MyObj.myObjs.join(", <br />*"));

实际结果

Old objName: undefined
New objName: result
Objects: 
*obj1, 
*obj2 - changed

期望的结果

Old objName: obj2
New objName: obj2 - changed
Objects: 
*obj1, 
*obj2 - changed

Answer 1

that.objName = name;
MyObj.myObjs[that.objIdx] = name;
that.doOnNameSet();

表示调用监听器时已经忘记了旧名称。我不确定你打算如何得到它。也许在您更改它之前调用监听器，将新名称作为参数。

obj2.doOnNameSet = function () {
     $("#console").append("Old objName: " + this.name
                          + "<br />New objName: " + name + "<br />");
};

该属性名为 objName，而 name 变量显然是未定义的。你想把它作为参数吗？