{ [key: string]: boolean; type { [key: string]: boolean;} 意思? [英] What does the type { [key: string]: boolean; } mean?

问题描述

最近遇到这样的事情，一个函数声明:

Run into such thing lately, a function declaration:

static required(control: AbstractControl): {
  [key: string]: boolean;
};

这个返回值是什么?具有任意数量属性的对象，其中每个属性都是布尔值并有一个名称，该名称似乎是一个字符串?我猜这更像是一个打字稿问题，但以防万一有人想知道我在哪里找到的 - 它是 Angular 的 Validators 类.

What is this return value? An object with an arbitrary amount of properties, where each of them is a boolean and has a name, which appears to be a string? It's more of a typescript question I guess, but just in case someone wonders where I found that - it's Angular's Validators class.

推荐答案

这是一个键/值结构.键是 string，值是 boolean.例如:

This is a key/value structure. The key is a string and the value is a boolean. For example:

let map : { [key: string]: boolean} = {};
map["foo"] = true;
map["bar"] = false;
map.foo = true;
map["foobar"] = "foo"; // Throws exception
map[1] = true; // Curiously doesn't throws exception

检查 Typescript Playground 上的这个示例.

可索引类型.

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