打字稿中的管道(|)是什么意思? [英] What does the pipe(|) mean in typescript?

问题描述

在浏览 @ng-bootstrap 的一些打字稿代码时，我发现了 pipe(|) 运算符.

While browsing some typescript code of @ng-bootstrap I have found pipe(|) operator.

export declare const NGB_PRECOMPILE: (typeof NgbAlert | typeof NgbTooltipWindow)[];

pipe(|) 运算符在打字稿中有什么用?

What is the use of pipe(|) operator in typescript?

推荐答案

这叫做 联合类型 在打字稿中.

This is called union type in typescript.

联合类型描述了一个可以是多种类型之一的值.

A union type describes a value that can be one of several types.

管道(|)用于分隔每种类型，例如number |字符串 |boolean 是值的类型，可以是 number、string 或 boolean.

Pipe (|) is used to separate each type, so for example number | string | boolean is the type of a value that can be a number, a string, or a boolean.

let something: number | string | boolean;

something = 1; // ok
something = '1'; // ok
something = true; // ok
something = {}; // Error: Type '{}' is not assignable to type 'string | number | boolean'

游乐场

这里有一个类似于问题中的例子:

And here's an example similar to one in the question:

class Test1 {
    public a: string
}

class Test2 {
    public b: string
}

class Test3 {
}

let x: (typeof Test1 | typeof Test2)[];

x = [Test1]; //ok
x = [Test1, Test2]; //ok
x = [Test3]; //compilation error

x 是一个包含 Test1 或 Test2 的构造函数的数组.

x is an array containing constructors of Test1 or Test2.

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