@use JSDoc

@external

Table of Contents

Synonyms

@host

Syntax

@external <NameOfExternal>

Overview

The @external tag identifies a class, namespace, or module that is defined outside of the current package. By using this tag, you can document your package's extensions to the external symbol, or you can provide information about the external symbol to your package's users. You can also refer to the external symbol's namepath in any other JSDoc tag.

The namepath for an external symbol always uses the prefix external: (for example, {@link external:Foo} or @augments external:Foo). However, you can omit this prefix from the @external tag.

Note: You should only add the @external tag to the highest-level symbol that is defined outside of your project. See "Documenting a nested external symbol" for an example.

Examples

The following example shows how to document the built-in String object as an external, along with the new instance method external:String#rot13:

Documenting methods added to built-in classes
/**
 * The built in string object.
 * @external String
 * @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String|String}
 */

/**
 * Create a ROT13-encoded version of the string. Added by the `foo` package.
 * @function external:String#rot13
 * @example
 * var greeting = new String('hello world');
 * console.log( greeting.rot13() ); // uryyb jbeyq
 */

The following example documents a new starfairy function added to the external namespace "jQuery.fn":

Documenting external namespaces
/**
 * The jQuery plugin namespace.
 * @external "jQuery.fn"
 * @see {@link http://learn.jquery.com/plugins/|jQuery Plugins}
 */

/**
 * A jQuery plugin to make stars fly around your home page.
 * @function external:"jQuery.fn".starfairy
 */

In the following example, the class EncryptedRequest is documented as a subclass of the built-in class XMLHttpRequest:

Extending an external.
/**
 * The built-in class for sending HTTP requests.
 * @external XMLHttpRequest
 * @see https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest
 */

/**
 * Extends the built-in `XMLHttpRequest` class to send data encoded with a secret key.
 * @class EncodedRequest
 * @extends external:XMLHttpRequest
 */

You should only add the @external tag to the highest-level symbol that is defined outside of your project. In the following example, the documentation refers to the external class security.TLS. As a result, the @external tag is used to document the external namespace external:security, but not the external class external:security.TLS.

Documenting a nested external symbol
/**
 * External namespace for security-related classes.
 * @external security
 * @see http://example.org/docs/security
 */

/**
 * External class that provides Transport Layer Security (TLS) encryption.
 * @class TLS
 * @memberof external:security
 */