typescript 在打字稿函数中声明“this”的类型？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/28920753/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Declaring the type of 'this' in a typescript function?
提问by Steve Cooper
I'm writing a grunt taskin TypeScript. I'm trying to translate something I already have in JavaScript.
我正在用 TypeScript编写一个grunt 任务。我正在尝试翻译我在 JavaScript 中已有的东西。
So, when grunt runs a task, it runs a function. When it runs, grunt sets thisto an object with useful properties, the same way that jQuery overloads thiswith the element you are working on. I could access useful properties like this.files;
所以，当 grunt 运行一个任务时，它运行一个函数。当它运行时，grunt 设置this为一个具有有用属性的对象，就像 jQuerythis用你正在处理的元素重载一样。我可以访问有用的属性，例如this.files；
grunt.registerMultiTask('clean', function() {
this.files.forEach(function(f) { Delete(f); });
});
So, "delete all the files in this.files".
因此，“删除”中的所有文件this.files。
However, in TypeScript, I don't know if you can 'hint' to the compiler that thisis a particular type, so I don't get intellisense. How do I tell TypeScript to consider thisto be a different type?
但是，在 TypeScript 中，我不知道您是否可以“暗示”this特定类型的编译器，因此我没有得到智能感知。我如何告诉 TypeScript 将其视为this不同的类型？
采纳答案by basarat
How do I tell TypeScript to consider this to be a different type
我如何告诉 TypeScript 将其视为不同的类型
There isn't a dedicated syntax for this yet but there are talks about it : https://github.com/Microsoft/TypeScript/issues/229
目前还没有专门的语法，但有关于它的讨论：https: //github.com/Microsoft/TypeScript/issues/229
For now what you have done is effectively the only way although I would not use an assertionand just use a type annotation:
现在你所做的是有效的唯一方法，尽管我不会使用断言而只使用类型注释：
var self:grunt.task.IMultiTask<string> = this;
self.files.forEach(function (f) {
});
回答by Aleksey L.
Now (from TS 2.0) you can specify function's thistype by using fake thisparameter (should be the first one):
现在（从 TS 2.0 开始）您可以this通过使用假这个参数（应该是第一个）来指定函数的类型：
grunt.registerMultiTask('clean', function(this: SomeType) {
//...
});
thisparameters are fake parameters that come first in the parameter list of a function
this参数是函数参数列表中最先出现的假参数
More info here
更多信息在这里
回答by Jason
While I found that is now possible with this:
虽然我发现现在可以这样做：
class ClassyClass {
prop = 'Juicy Strings'
}
function x( this: ClassyClass ) {
console.log( this.prop )
}
I have come prefer an alternative that doesn't take up real estate in the arguments line
我更喜欢在参数行中不占用房地产的替代方案
function x() {
const that: ClassyClass = this
console.log( that.prop )
}
回答by Steve Cooper
I have a bit of an answer. I can do this;
我有点答案。我可以做这个;
var self = <grunt.task.IMultiTask<string>>this;
self.files.forEach(function (f) {
});
which works OK. It's gonna have consequences, like not being able to write arrow functions...
这工作正常。它会产生后果，比如无法编写箭头函数......
