Question

您好我收到错误this._radioButtons未定义（**之间的代码）在下面的代码段中。我在这里找不到关闭的东西吗？

_adjustChoices: function(choices) {
            // TODO Tear down all the old radion buttons and their change handlers.
            debugger;
            this._radioButtons = [];
            this._changeHandlers = [];
            array.forEach(choices, function(choice) {
                var radioButton = new RadioButton(lang.mixin({
                    name: this._clusterName
                }, choice));
                **this._radioButtons.push(radioButton);**
                this._changeHandlers.push(connect.connect, radioButton, "onChange", lang.hitch(this, function(value) {
                    // TODO Figure out which radio button is selected and get its value.
                    //var radioButton = ????;
                    this.set("value", radioButton.get("checked"));
                }));
            });
        },

Answer 1

您在array.forEach(choices, function(choice) { /* your code here*/ })回调函数内，因此this指的是函数。添加this作为强制上下文的第三个参数：

array.forEach(choices, function(choice) { 

    // YOUR CODE HERE

}, this);  // => here

Answer 2

在我个人看来，可以通过在错误的功能范围之外声明某种指针来改善可读性，例如

// code code code
_adjustChoices: function(choices) {
    var _this = this;
    // rest of your code...

    array.forEach(choices, function(choice) {
        //stuff you do
        var radioButton = new RadioButton(lang.mixin({
                name: _this._clusterName                //access it this way
            }, choice));
    }
}

这样，就可以访问每个this - 指针，甚至命名为this_adustChoices或诸如此类......

this.variable未定义

2 个答案: