this != JavaScript 中的 this （好吧，有时......）
示例 1
var Reptile = function () {
var reptile = this;
this.showBla = function() {
alert(reptile.bla);
}
}
var turtle = new Reptile();
turtle.bla = 'whatever';
turtle.showBla();
示例 2
var Reptile = function () {
this.showBla = function() {
alert(this.bla);
}
}
var turtle = new Reptile();
turtle.bla = 'whatever';
turtle.showBla();
示例 1 合法吗？因为有时直接在构造函数中定义“this”似乎把事情搞砸了......？！？
Example 1
var Reptile = function () {
var reptile = this;
this.showBla = function() {
alert(reptile.bla);
}
}
var turtle = new Reptile();
turtle.bla = 'whatever';
turtle.showBla();
Example 2
var Reptile = function () {
this.showBla = function() {
alert(this.bla);
}
}
var turtle = new Reptile();
turtle.bla = 'whatever';
turtle.showBla();
Is example 1 legit? As it sometimes seems to screw things over to define "this" directly in the constructor...?!?
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评论（2）
是的，它是合法的，并且在您可能需要在函数内定义一个函数并且可以以“this”将指向其他内容的方式调用的情况下很有用。书籍建议将此变量命名为 var that = this;
Yes, it is legit and is useful in cases where you may need to define a function inside a function that may be invoked in a way there "this" will pointer to something else. Books recommend naming this variable var that = this;
示例 1 是维护对当前实例的引用的常见模式。在回调情况下，例如：
示例 1 的
var reptile...保存this引用并显示'whatever'。示例 2 将显示undefined，除非您在调用方手动分配范围（例如，在 jQuery 中）：Example 1 is a common pattern for maintaining the reference to the current instance. In a callback situation, like:
Example 1's
var reptile...saves thethisreference and will show'whatever'. Example 2 will showundefined, unless you manually assign scope on the calling side (e.g., in jQuery):