JSDoc 参考资料

下面的列表概述了在使用 JSDoc 注释在 JavaScript 文件中提供类型信息时当前支持哪些结构。

¥The list below outlines which constructs are currently supported when using JSDoc annotations to provide type information in JavaScript files.

注意：

¥Note:

• 尚不支持任何未在下面明确列出的标签（例如 @async）。

  ¥Any tags which are not explicitly listed below (such as @async) are not yet supported.

• TypeScript 文件中仅支持文档标签。其余标签仅在 JavaScript 文件中受支持。

  ¥Only documentation tags are supported in TypeScript files. The rest of the tags are only supported in JavaScript files.

类型

¥Types

• @type

• @param（或 @arg 或 @argument）

  ¥@param (or @arg or @argument)

• @returns（或 @return）

  ¥@returns (or @return)

• @typedef

• @callback

• @template

• @satisfies

类

¥Classes

• 属性修饰符 @public, @private, @protected, @readonly

  ¥Property Modifiers @public, @private, @protected, @readonly

• @override

• @extends（或 @augments）

  ¥@extends (or @augments)

• @implements

• @class（或 @constructor）

  ¥@class (or @constructor)

• @this

文档

¥Documentation

文档标签适用于 TypeScript 和 JavaScript。

¥Documentation tags work in both TypeScript and JavaScript.

• @deprecated

• @see

• @link

其他

¥Other

• @enum

• @author

• 其他支持的模式

  ¥Other supported patterns

• 不支持的模式

  ¥Unsupported patterns

• 不支持的标签

  ¥Unsupported tags

含义通常与 jsdoc.app 处给出的标签的含义相同或超集。下面的代码描述了差异并给出了每个标签的一些示例用法。

¥The meaning is usually the same, or a superset, of the meaning of the tag given at jsdoc.app. The code below describes the differences and gives some example usage of each tag.

注意：你可以使用 探索 JSDoc 支持的在线运行。

¥Note: You can use the playground to explore JSDoc support.

类型

¥Types

@type

你可以使用 “@type” 标记引用类型。类型可以是：

¥You can reference types with the “@type” tag. The type can be:

1. 基础类型，如 string 或 number。

   ¥Primitive, like string or number.

2. 在 TypeScript 声明中声明，全局或导入。

   ¥Declared in a TypeScript declaration, either global or imported.

3. 在 JSDoc @typedef 标签中声明。

   ¥Declared in a JSDoc @typedef tag.

你可以使用大多数 JSDoc 类型语法和任何 TypeScript 语法，从 最基本的像 string 到 最高级的，比如条件类型。

¥You can use most JSDoc type syntax and any TypeScript syntax, from the most basic like string to the most advanced, like conditional types.

js
/**
 
 * @type {string}
 */
var s;
 
/** @type {Window} */
var win;
 
/** @type {PromiseLike<string>} */
var promisedString;
 
// You can specify an HTML Element with DOM properties
/** @type {HTMLElement} */
var myElement = document.querySelector(selector);
element.dataset.myData = "";Try

@type 可以指定联合类型 - 例如，某些内容可以是字符串或布尔值。

¥@type can specify a union type — for example, something can be either a string or a boolean.

js
/**
 
 * @type {string | boolean}
 */
var sb;Try

你可以使用多种语法指定数组类型：

¥You can specify array types using a variety of syntaxes:

js
/** @type {number[]} */
var ns;
/** @type {Array.<number>} */
var jsdoc;
/** @type {Array<number>} */
var nas;Try

你还可以指定对象字面类型。例如，具有属性 ‘a’（字符串）和 ‘b’（数字）的对象使用以下语法：

¥You can also specify object literal types. For example, an object with properties ‘a’ (string) and ‘b’ (number) uses the following syntax:

js
/** @type {{ a: string, b: number }} */
var var9;Try

你可以使用标准 JSDoc 语法或 TypeScript 语法，使用字符串和数字索引签名来指定类映射和类数组对象。

¥You can specify map-like and array-like objects using string and number index signatures, using either standard JSDoc syntax or TypeScript syntax.

js
/**
 
 * A map-like object that maps arbitrary `string` properties to `number`s.
 
 *  * @type {Object.<string, number>}
 */
var stringToNumber;
 
/** @type {Object.<number, object>} */
var arrayLike;Try

上述两种类型相当于 TypeScript 类型 { [x: string]: number } 和 { [x: number]: any }。编译器理解这两种语法。

¥The preceding two types are equivalent to the TypeScript types { [x: string]: number } and { [x: number]: any }. The compiler understands both syntaxes.

你可以使用 TypeScript 或 Google Closure 语法指定函数类型：

¥You can specify function types using either TypeScript or Google Closure syntax:

js
/** @type {function(string, boolean): number} Closure syntax */
var sbn;
/** @type {(s: string, b: boolean) => number} TypeScript syntax */
var sbn2;Try

或者你可以只使用未指定的 Function 类型：

¥Or you can just use the unspecified Function type:

js
/** @type {Function} */
var fn7;
/** @type {function} */
var fn6;Try

Closure 的其他类型也可以工作：

¥Other types from Closure also work:

js
/**
 
 * @type {*} - can be 'any' type
 */
var star;
/**
 
 * @type {?} - unknown type (same as 'any')
 */
var question;Try

Casts

TypeScript 借鉴了 Google Closure 的强制转换语法。这使你可以通过在任何带括号的表达式之前添加 @type 标记来将类型转换为其他类型。

¥TypeScript borrows cast syntax from Google Closure. This lets you cast types to other types by adding a @type tag before any parenthesized expression.

js
/**
 
 * @type {number | string}
 */
var numberOrString = Math.random() < 0.5 ? "hello" : 100;
var typeAssertedNumber = /** @type {number} */ (numberOrString);Try

你甚至可以像 TypeScript 一样转换为 const：

¥You can even cast to const just like TypeScript:

js
let one = /** @type {const} */(1);Try

导入类型

¥Import types

你可以使用导入类型从其他文件导入声明。此语法特定于 TypeScript，与 JSDoc 标准不同：

¥You can import declarations from other files using import types. This syntax is TypeScript-specific and differs from the JSDoc standard:

js
// @filename: types.d.ts
export type Pet = {
  name: string,
};
 
// @filename: main.js
/**
 
 * @param {import("./types").Pet} p
 */
function walk(p) {
  console.log(`Walking ${p.name}...`);
}Try

导入类型可以在类型别名声明中使用：

¥import types can be used in type alias declarations:

js
/**
 
 * @typedef {import("./types").Pet} Pet
 */
 
/**
 
 * @type {Pet}
 */
var myPet;
myPet.name;Try

import types 可以用来从模块中获取值的类型，如果你不知道类型，或者如果它有一个大的类型，输入起来很烦人：

¥import types can be used to get the type of a value from a module if you don’t know the type, or if it has a large type that is annoying to type:

js
/**
 
 * @type {typeof import("./accounts").userAccount}
 */
var x = require("./accounts").userAccount;Try

@param 和 @returns

¥@param and @returns

@param 使用与 @type 相同的类型语法，但添加了参数名称。该参数也可以通过用方括号括起名称来声明为可选：

¥@param uses the same type syntax as @type, but adds a parameter name. The parameter may also be declared optional by surrounding the name with square brackets:

js
// Parameters may be declared in a variety of syntactic forms
/**
 
 * @param {string}  p1 - A string param.
 
 * @param {string=} p2 - An optional param (Google Closure syntax)
 
 * @param {string} [p3] - Another optional param (JSDoc syntax).
 
 * @param {string} [p4="test"] - An optional param with a default value
 
 * @returns {string} This is the result
 */
function stringsStringStrings(p1, p2, p3, p4) {
  // TODO
}Try

同样，对于函数的返回类型：

¥Likewise, for the return type of a function:

js
/**
 
 * @return {PromiseLike<string>}
 */
function ps() {}
 
/**
 
 * @returns {{ a: string, b: number }} - May use '@returns' as well as '@return'
 */
function ab() {}Try

@typedef、@callback 和 @param

¥@typedef, @callback, and @param

你可以使用 @typedef 定义复杂类型。类似的语法适用于 @param。

¥You can define complex types with @typedef. Similar syntax works with @param.

js
/**
 
 * @typedef {Object} SpecialType - creates a new type named 'SpecialType'
 
 * @property {string} prop1 - a string property of SpecialType
 
 * @property {number} prop2 - a number property of SpecialType
 
 * @property {number=} prop3 - an optional number property of SpecialType
 
 * @prop {number} [prop4] - an optional number property of SpecialType
 
 * @prop {number} [prop5=42] - an optional number property of SpecialType with default
 */
 
/** @type {SpecialType} */
var specialTypeObject;
specialTypeObject.prop3;Try

你可以在第一行使用 object 或 Object。

¥You can use either object or Object on the first line.

js
/**
 
 * @typedef {object} SpecialType1 - creates a new type named 'SpecialType1'
 
 * @property {string} prop1 - a string property of SpecialType1
 
 * @property {number} prop2 - a number property of SpecialType1
 
 * @property {number=} prop3 - an optional number property of SpecialType1
 */
 
/** @type {SpecialType1} */
var specialTypeObject1;Try

@param 允许对一次性类型规范使用类似的语法。请注意，嵌套的属性名称必须以参数名称为前缀：

¥@param allows a similar syntax for one-off type specifications. Note that the nested property names must be prefixed with the name of the parameter:

js
/**
 
 * @param {Object} options - The shape is the same as SpecialType above
 
 * @param {string} options.prop1
 
 * @param {number} options.prop2
 
 * @param {number=} options.prop3
 
 * @param {number} [options.prop4]
 
 * @param {number} [options.prop5=42]
 */
function special(options) {
  return (options.prop4 || 1001) + options.prop5;
}Try

@callback 与 @typedef 类似，但它指定的是函数类型而不是对象类型：

¥@callback is similar to @typedef, but it specifies a function type instead of an object type:

js
/**
 
 * @callback Predicate
 
 * @param {string} data
 
 * @param {number} [index]
 
 * @returns {boolean}
 */
 
/** @type {Predicate} */
const ok = (s) => !(s.length % 2);Try

当然，这些类型中的任何一种都可以在单行 @typedef 中使用 TypeScript 语法声明：

¥Of course, any of these types can be declared using TypeScript syntax in a single-line @typedef:

js
/** @typedef {{ prop1: string, prop2: string, prop3?: number }} SpecialType */
/** @typedef {(data: string, index?: number) => boolean} Predicate */

@template

你可以使用 @template 标记声明类型参数。这使你可以创建泛型的函数、类或类型：

¥You can declare type parameters with the @template tag. This lets you make functions, classes, or types that are generic:

js
/**
 
 * @template T
 
 * @param {T} x - A generic parameter that flows through to the return type
 
 * @returns {T}
 */
function id(x) {
  return x;
}
 
const a = id("string");
const b = id(123);
const c = id({});Try

使用逗号或多个标签来声明多个类型参数：

¥Use comma or multiple tags to declare multiple type parameters:

js
/**
 * @template T,U,V
 * @template W,X
 */

你还可以在类型参数名称之前指定类型约束。只有列表中的第一个类型参数受到约束：

¥You can also specify a type constraint before the type parameter name. Only the first type parameter in a list is constrained:

js
/**
 
 * @template {string} K - K must be a string or string literal
 
 * @template {{ serious(): string }} Seriousalizable - must have a serious method
 
 * @param {K} key
 
 * @param {Seriousalizable} object
 */
function seriousalize(key, object) {
  // ????
}Try

最后，你可以为类型参数指定默认值：

¥Finally, you can specify a default for a type parameter:

js
/** @template [T=object] */
class Cache {
    /** @param {T} initial */
    constructor(initial) {
    }
}
let c = new Cache()Try

@satisfies

@satisfies 提供对 TypeScript 中后缀 运算符 satisfies 的访问。Satisfies 用于声明某个值实现了某种类型，但不影响该值的类型。

¥@satisfies provides access to the postfix operator satisfies in TypeScript. Satisfies is used to declare that a value implements a type but does not affect the type of the value.

js
// @ts-check
/**
 
 * @typedef {"hello world" | "Hello, world"} WelcomeMessage
 */
 
/** @satisfies {WelcomeMessage} */
const message = "hello world"
        
const message: "hello world"
 
/** @satisfies {WelcomeMessage} */
Type '"Hello world!"' does not satisfy the expected type 'WelcomeMessage'.1360Type '"Hello world!"' does not satisfy the expected type 'WelcomeMessage'.
const failingMessage = "Hello world!"
 
/** @type {WelcomeMessage} */
const messageUsingType = "hello world"
             
const messageUsingType: WelcomeMessageTry

类

¥Classes

类可以声明为 ES6 类。

¥Classes can be declared as ES6 classes.

js
class C {
  /**
 
   * @param {number} data
   */
  constructor(data) {
    // property types can be inferred
    this.name = "foo";
 
    // or set explicitly
    /** @type {string | null} */
    this.title = null;
 
    // or simply annotated, if they're set elsewhere
    /** @type {number} */
    this.size;
 
    this.initialize(data); // Should error, initializer expects a string
  }
  /**
 
   * @param {string} s
   */
  initialize = function (s) {
    this.size = s.length;
  };
}
 
var c = new C(0);
 
// C should only be called with new, but
// because it is JavaScript, this is allowed and
// considered an 'any'.
var result = C(1);Try

它们也可以声明为构造函数；为此使用 @constructor 和 @this。

¥They can also be declared as constructor functions; use @constructor along with @this for this.

属性修饰符

¥Property Modifiers

@public、@private 和 @protected 在 TypeScript 中的工作方式与 public、private 和 protected 完全相同：

¥@public, @private, and @protected work exactly like public, private, and protected in TypeScript:

js
// @ts-check
 
class Car {
  constructor() {
    /** @private */
    this.identifier = 100;
  }
 
  printIdentifier() {
    console.log(this.identifier);
  }
}
 
const c = new Car();
console.log(c.identifier);
Property 'identifier' is private and only accessible within class 'Car'.2341Property 'identifier' is private and only accessible within class 'Car'.Try

• @public 总是隐含的，可以省略，但表示可以从任何地方访问属性。

  ¥@public is always implied and can be left off, but means that a property can be reached from anywhere.

• @private 表示属性只能在包含类中使用。

  ¥@private means that a property can only be used within the containing class.

• @protected 表示属性只能在包含类和所有派生子类中使用，但不能在包含类的不同实例上使用。

  ¥@protected means that a property can only be used within the containing class, and all derived subclasses, but not on dissimilar instances of the containing class.

@public、@private 和 @protected 在构造函数中不起作用。

¥@public, @private, and @protected do not work in constructor functions.

@readonly

@readonly 修饰符确保只在初始化期间写入属性。

¥The @readonly modifier ensures that a property is only ever written to during initialization.

js
// @ts-check
 
class Car {
  constructor() {
    /** @readonly */
    this.identifier = 100;
  }
 
  printIdentifier() {
    console.log(this.identifier);
  }
}
 
const c = new Car();
console.log(c.identifier);Try

@override

@override 的工作方式与 TypeScript 相同；在覆盖基类方法的方法上使用它：

¥@override works the same way as in TypeScript; use it on methods that override a method from a base class:

js
export class C {
  m() { }
}
class D extends C {
  /** @override */
  m() { }
}Try

在 tsconfig 中设置 noImplicitOverride: true 以检查覆盖。

¥Set noImplicitOverride: true in tsconfig to check overrides.

@extends

当 JavaScript 类扩展泛型基类时，没有用于传递类型参数的 JavaScript 语法。@extends 标签允许这样：

¥When JavaScript classes extend a generic base class, there is no JavaScript syntax for passing a type argument. The @extends tag allows this:

js
/**
 
 * @template T
 
 * @extends {Set<T>}
 */
class SortableSet extends Set {
  // ...
}Try

请注意，@extends 仅适用于类。目前，构造函数无法扩展类。

¥Note that @extends only works with classes. Currently, there is no way for a constructor function to extend a class.

@implements

同样，没有用于实现 TypeScript 接口的 JavaScript 语法。@implements 标签就像在 TypeScript 中一样工作：

¥In the same way, there is no JavaScript syntax for implementing a TypeScript interface. The @implements tag works just like in TypeScript:

js
/** @implements {Print} */
class TextBook {
  print() {
    // TODO
  }
}Try

@constructor

编译器根据 this-property 赋值推断构造函数，但如果添加 @constructor 标记，则可以使检查更严格并提供更好的建议：

¥The compiler infers constructor functions based on this-property assignments, but you can make checking stricter and suggestions better if you add a @constructor tag:

js
/**
 
 * @constructor
 
 * @param {number} data
 */
function C(data) {
  // property types can be inferred
  this.name = "foo";
 
  // or set explicitly
  /** @type {string | null} */
  this.title = null;
 
  // or simply annotated, if they're set elsewhere
  /** @type {number} */
  this.size;
 
  this.initialize(data);
Argument of type 'number' is not assignable to parameter of type 'string'.2345Argument of type 'number' is not assignable to parameter of type 'string'.
}
/**
 
 * @param {string} s
 */
C.prototype.initialize = function (s) {
  this.size = s.length;
};
 
var c = new C(0);
c.size;
 
var result = C(1);
Value of type 'typeof C' is not callable. Did you mean to include 'new'?2348Value of type 'typeof C' is not callable. Did you mean to include 'new'?Try

注意：错误消息仅显示在启用了 一个 JSConfig 和 checkJs 的 JS 代码库中。

¥Note: Error messages only show up in JS codebases with a JSConfig and checkJs enabled.

对于 @constructor，this 在构造函数 C 中进行检查，因此你将获得 initialize 方法的建议，如果你向它传递一个数字，则会出现错误。如果你调用 C 而不是构造它，你的编辑器也可能会显示警告。

¥With @constructor, this is checked inside the constructor function C, so you will get suggestions for the initialize method and an error if you pass it a number. Your editor may also show warnings if you call C instead of constructing it.

不幸的是，这意味着同样可调用的构造函数不能使用 @constructor。

¥Unfortunately, this means that constructor functions that are also callable cannot use @constructor.

@this

当编译器有一些上下文可以使用时，它通常可以找出 this 的类型。如果没有，你可以使用 @this 显式指定 this 的类型：

¥The compiler can usually figure out the type of this when it has some context to work with. When it doesn’t, you can explicitly specify the type of this with @this:

js
/**
 
 * @this {HTMLElement}
 
 * @param {*} e
 */
function callbackForLater(e) {
  this.clientHeight = parseInt(e); // should be fine!
}Try

文档

¥Documentation

@deprecated

当一个函数、方法或属性被弃用时，你可以通过用 /** @deprecated */ JSDoc 注释标记它来让用户知道。该信息显示在完成列表中，并作为编辑可以专门处理的建议诊断。在 VS Code 等编辑器中，不推荐使用的值通常以删除线样式 like this 显示。

¥When a function, method, or property is deprecated you can let users know by marking it with a /** @deprecated */ JSDoc comment. That information is surfaced in completion lists and as a suggestion diagnostic that editors can handle specially. In an editor like VS Code, deprecated values are typically displayed in a strike-through style like this.

js
/** @deprecated */
const apiV1 = {};
const apiV2 = {};
 
apiV;
   
apiV1
apiV2
 
 Try

@see

@see 允许你链接到程序中的其他名称：

¥@see lets you link to other names in your program:

ts
type Box<T> = { t: T }
/** @see Box for implementation details */
type Boxify<T> = { [K in keyof T]: Box<T> };Try

一些编辑器会将 Box 变成一个链接，以便于跳转和返回。

¥Some editors will turn Box into a link to make it easy to jump there and back.

@link

@link 与 @see 类似，只是它可以在其他标签内使用：

¥@link is like @see, except that it can be used inside other tags:

ts
type Box<T> = { t: T }
/** @returns A {@link Box} containing the parameter. */
function box<U>(u: U): Box<U> {
  return { t: u };
}Try

其他

¥Other

@enum

@enum 标记允许你创建一个对象字面，其成员都是指定类型。与 JavaScript 中的大多数对象字面不同，它不允许其他成员。@enum 旨在与 Google Closure 的 @enum 标签兼容。

¥The @enum tag allows you to create an object literal whose members are all of a specified type. Unlike most object literals in JavaScript, it does not allow other members. @enum is intended for compatibility with Google Closure’s @enum tag.

js
/** @enum {number} */
const JSDocState = {
  BeginningOfLine: 0,
  SawAsterisk: 1,
  SavingComments: 2,
};
 
JSDocState.SawAsterisk;Try

请注意，@enum 与 TypeScript 的 enum 截然不同，而且简单得多。然而，与 TypeScript 的枚举不同，@enum 可以是任何类型：

¥Note that @enum is quite different from, and much simpler than, TypeScript’s enum. However, unlike TypeScript’s enums, @enum can have any type:

js
/** @enum {function(number): number} */
const MathFuncs = {
  add1: (n) => n + 1,
  id: (n) => -n,
  sub1: (n) => n - 1,
};
 
MathFuncs.add1;Try

@author

你可以使用 @author 指定项目的作者：

¥You can specify the author of an item with @author:

ts
/**
 
 * Welcome to awesome.ts
 
 * @author Ian Awesome <i.am.awesome@example.com>
 */Try

请记住用尖括号将电邮地址括起来。否则，@example 将被解析为新标签。

¥Remember to surround the email address with angle brackets. Otherwise, @example will be parsed as a new tag.

其他支持的模式

¥Other supported patterns

js
var someObj = {
  /**
 
   * @param {string} param1 - JSDocs on property assignments work
   */
  x: function (param1) {},
};
 
/**
 
 * As do jsdocs on variable assignments
 
 * @return {Window}
 */
let someFunc = function () {};
 
/**
 
 * And class methods
 
 * @param {string} greeting The greeting to use
 */
Foo.prototype.sayHi = (greeting) => console.log("Hi!");
 
/**
 
 * And arrow function expressions
 
 * @param {number} x - A multiplier
 */
let myArrow = (x) => x * x;
 
/**
 
 * Which means it works for function components in JSX too
 
 * @param {{a: string, b: number}} props - Some param
 */
var fc = (props) => <div>{props.a.charAt(0)}</div>;
 
/**
 
 * A parameter can be a class constructor, using Google Closure syntax.
 
 *  * @param {{new(...args: any[]): object}} C - The class to register
 */
function registerClass(C) {}
 
/**
 
 * @param {...string} p1 - A 'rest' arg (array) of strings. (treated as 'any')
 */
function fn10(p1) {}
 
/**
 
 * @param {...string} p1 - A 'rest' arg (array) of strings. (treated as 'any')
 */
function fn9(p1) {
  return p1.join();
}Try

不支持的模式

¥Unsupported patterns

对象字面类型中属性类型的后缀等于未指定可选属性：

¥Postfix equals on a property type in an object literal type doesn’t specify an optional property:

js
/**
 
 * @type {{ a: string, b: number= }}
 */
var wrong;
/**
 
 * Use postfix question on the property name instead:
 
 * @type {{ a: string, b?: number }}
 */
var right;Try

可空类型只有在 strictNullChecks 打开时才有意义：

¥Nullable types only have meaning if strictNullChecks is on:

js
/**
 
 * @type {?number}
 
 * With strictNullChecks: true  -- number | null
 
 * With strictNullChecks: false -- number
 */
var nullable;Try

TypeScript 原生语法是联合类型：

¥The TypeScript-native syntax is a union type:

js
/**
 
 * @type {number | null}
 
 * With strictNullChecks: true  -- number | null
 
 * With strictNullChecks: false -- number
 */
var unionNullable;Try

不可为 null 的类型没有意义，并被视为它们的基础类型：

¥Non-nullable types have no meaning and are treated just as their original type:

js
/**
 
 * @type {!number}
 
 * Just has type number
 */
var normal;Try

与 JSDoc 的类型系统不同，TypeScript 只允许你将类型标记为包含或不包含 null。没有明确的不可空性 - 如果启用了 strictNullChecks，则 number 不可空。如果关闭，则 number 可为空。

¥Unlike JSDoc’s type system, TypeScript only allows you to mark types as containing null or not. There is no explicit non-nullability — if strictNullChecks is on, then number is not nullable. If it is off, then number is nullable.

不支持的标签

¥Unsupported tags

TypeScript 会忽略任何不受支持的 JSDoc 标签。

¥TypeScript ignores any unsupported JSDoc tags.

以下标签有未解决的问题来支持它们：

¥The following tags have open issues to support them:

• @memberof(问题 #7237)

  ¥@memberof (issue #7237)

• @yields(问题 #23857)

  ¥@yields (issue #23857)

• @member(问题 #56674)

  ¥@member (issue #56674)

旧版类型同义词

¥Legacy type synonyms

为了与旧的 JavaScript 代码兼容，许多常见类型都被赋予了别名。一些别名与现有类型相同，尽管大多数别名很少使用。例如，String 被视为 string 的别名。尽管 String 是 TypeScript 中的一种类型，但旧的 JSDoc 经常使用它来表示 string。此外，在 TypeScript 中，原始类型的大写版本是封装器类型 - 几乎总是使用错误。因此，编译器根据旧 JSDoc 中的用法将这些类型视为同义词：

¥A number of common types are given aliases for compatibility with old JavaScript code. Some of the aliases are the same as existing types, although most of those are rarely used. For example, String is treated as an alias for string. Even though String is a type in TypeScript, old JSDoc often uses it to mean string. Besides, in TypeScript, the capitalized versions of primitive types are wrapper types — almost always a mistake to use. So the compiler treats these types as synonyms based on usage in old JSDoc:

• String -> string

• Number -> number

• Boolean -> boolean

• Void -> void

• Undefined -> undefined

• Null -> null

• function -> Function

• array -> Array<any>

• promise -> Promise<any>

• Object -> any

• object -> any

当 noImplicitAny: true 时，最后四个别名被关闭：

¥The last four aliases are turned off when noImplicitAny: true:

• object 和 Object 是内置类型，尽管 Object 很少使用。

  ¥object and Object are built-in types, although Object is rarely used.

• array 和 promise 不是内置的，但可能在程序中的某个地方声明。

  ¥array and promise are not built-in, but might be declared somewhere in your program.