javascript - this.variable 未定义

Question

您好，我在以下代码片段中收到错误 this._radioButtons 未定义( ** 之间的代码)。我在这里遗漏了一些有关闭包的信息吗？

_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

您位于 array.forEach(choices, function(choice) {/* your code here*/}) 回调函数内，因此 this 引用该函数。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