数组<类型>VS Type[] 在打字稿中 [英] Array&lt;Type&gt; VS Type[] in Typescript

问题描述

据我所知，当它是一个数组时，可以通过两种方式定义一个属性的类型.

As far as I know a property's type can be defined in two ways when it's an Array.

property_name: type

类型可以是其中之一

Array<string>, Array<MyType>, etc. (e.g. let prop1: Array<string>)

和

string[], MyType[], etc. (e.g. let prop1: string[])

这两种情况之间的区别是什么?或者我误解了什么(也许是关于 <> 在铸造中使用的?)

What is the difference between the two cases? Or am I misunderstanding something (perhaps something about <> used in casting?)

EDIT 由于问题被标记为重复，我知道还有一个关于 any[] 的问题，但在发布之前我仍然看过它，对我来说更多的是关于类型'any' 比不同的 [] VS <> 我问

EDIT since the question is marked as duplicate, I am aware there is the other question about any[] but still I had a look at it before posting and to me it was more about the type 'any' than the different [] VS <> I asked

推荐答案

没有任何语义差异

完全没有区别.Type[] 是 Type 数组的速记语法.Array 是通用语法.它们完全等效.

There isn't any semantic difference

There is no difference at all. Type[] is the shorthand syntax for an array of Type. Array<Type> is the generic syntax. They are completely equivalent.

手册提供了此处的示例.相当于写:

The handbook provides an example here. It is equivalent to write:

function loggingIdentity<T>(arg: T[]): T[] {
    console.log(arg.length);
    return arg;
}

或者:

function loggingIdentity<T>(arg: Array<T>): Array<T> {
    console.log(arg.length);
    return arg;
}

这里引用了 一些发行说明:

具体来说，number[] 是 Array 的简写版本，就像 Date[] 是 的简写一样>数组<日期>.

Specifically, number[] is a shorthand version of Array<number>, just as Date[] is a shorthand for Array<Date>.

关于readonly 类型修饰符

TypeScript 3.4，引入了 readonly 类型修饰符.使用 精确:

About the readonly type modifier

TypeScript 3.4, introduces the readonly type modifier. With a precision:

readonly 类型修饰符只能用于数组类型和元组类型的语法

the readonly type modifier can only be used for syntax on array types and tuple types

let err2: readonly Array<boolean>; // error!    
let okay: readonly boolean[]; // works fine

以下声明等价于readonly boolean[]:

let okay2: ReadonlyArray<boolean>;

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