什么是Typescript中的new()? [英] what is new() in Typescript?
问题描述
我在官方文档中遇到 new()
这里。
I encountered new()
in the official document here about generics.
以下是代码上下文:
function create<T>(c: { new(): T; } ): T {
return new c();
}
以上代码转换为以下JavaScript代码:
The above code is transpiled to the following JavaScript code:
function create(c) {
return new c();
}
new()
是JavaScript中的非法语法。 TypeScript是什么意思?
new()
is illegal syntax in JavaScript. What does it mean in TypeScript?
此外, {new():T; }
是什么意思?我知道它必须是一种类型,但如何?
Furthermore, what does {new(): T; }
mean? I know it must be a type, but how?
推荐答案
new()
描述了typescript中的构造函数签名。这意味着它描述了构造函数的形状。
例如,取 {new():T; }
。你是对的它是一种类型。它是类的类型,其构造函数不带参数。请考虑以下示例
new()
describes a constructor signature in typescript. What that means is that it describes the shape of the constructor.
For instance take {new(): T; }
. You are right it is a type. It is the type of a class whose constructor takes in no arguments. Consider the following examples
function create<T>(c: { new(): T; } ): T {
return new c();
}
这意味着函数 create
接受一个参数,其构造函数不带参数,并返回类型 T
的实例。
What this means is that the function create
takes an argument whose constructor takes no arguments and returns an instance of type T
.
function create<T>(c: { new(a: number): T; } ): T
这意味着create函数接受一个参数,其构造函数接受一个数字 a
并返回类型为T. $ b的实例$ b解释它的另一种方法可以是,以下类的类型
What this would mean is that the create function takes an argument whose constructor accepts one number a
and returns an instance of type T.
Another way to explain it can be, the type of the following class
class Test {
constructor(a: number){
}
}
将 {new(a:number):Test}
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