声明参考手册

本指南的目的是教您如何编写高质量的定义文件。本指南的结构是展示一些 API 的文档，以及该 API 的示例用法，并解释如何编写相应的声明。

这些示例按复杂程度大致递增的顺序排列。

具有属性的对象

文档

全局变量 myLib 有一个函数 makeGreeting 用于创建问候语，还有一个属性 numberOfGreetings 表示到目前为止问候语的数量。

代码

let result = myLib.makeGreeting("hello, world");
console.log("The computed greeting is:" + result);

let count = myLib.numberOfGreetings;

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declare namespace myLib {
  function makeGreeting(s: string): string;
  let numberOfGreetings: number;
}

重载函数

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let x: Widget = getWidget(43);

let arr: Widget[] = getWidget("all of them");

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declare function getWidget(n: number): Widget;
declare function getWidget(s: string): Widget[];

可重用类型（接口）

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greet({
  greeting: "hello world",
  duration: 4000
});

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interface GreetingSettings {
  greeting: string;
  duration?: number;
  color?: string;
}

declare function greet(setting: GreetingSettings): void;

可重用类型（类型别名）

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function getGreeting() {
  return "howdy";
}
class MyGreeter extends Greeter {}

greet("hello");
greet(getGreeting);
greet(new MyGreeter());

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type GreetingLike = string | (() => string) | MyGreeter;

declare function greet(g: GreetingLike): void;

组织类型

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const g = new Greeter("Hello");
g.log({ verbose: true });
g.alert({ modal: false, title: "Current Greeting" });

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declare namespace GreetingLib {
  interface LogOptions {
    verbose?: boolean;
  }
  interface AlertOptions {
    modal: boolean;
    title?: string;
    color?: string;
  }
}

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declare namespace GreetingLib.Options {
  // Refer to via GreetingLib.Options.Log
  interface Log {
    verbose?: boolean;
  }
  interface Alert {
    modal: boolean;
    title?: string;
    color?: string;
  }
}

类

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const myGreeter = new Greeter("hello, world");
myGreeter.greeting = "howdy";
myGreeter.showGreeting();

class SpecialGreeter extends Greeter {
  constructor() {
    super("Very special greetings");
  }
}

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declare class Greeter {
  constructor(greeting: string);

  greeting: string;
  showGreeting(): void;
}

全局变量

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console.log("Half the number of widgets is " + foo / 2);

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/** The number of widgets present */
declare var foo: number;

全局函数

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greet("hello, world");

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declare function greet(greeting: string): void;