Hooks

A lightweight & efficient EventManager for JavaScript.

Installation

Install the module

npm install @wordpress/hooks --save

This package assumes that your code will run in an ES2015+ environment. If you're using an environment that has limited or no support for such language features and APIs, you should include the polyfill shipped in @wordpress/babel-preset-default in your code.

Usage

In your JavaScript project, use hooks as follows:

import { createHooks } from '@wordpress/hooks';

myObject.hooks = createHooks();
myObject.hooks.addAction(); //etc...

The global instance

In the above example, we are creating a custom instance of the Hooks object and registering hooks there. The package also creates a default global instance that's accessible through the defaultHooks named exports, and its methods are also separately exported one-by-one.

In the WordPress context, that enables API functions to be called via the global wp.hooks object, like wp.hooks.addAction(), etc.

One notable difference between the JS and PHP hooks API is that in the JS version, addAction() and addFilter() also need to include a namespace as the second argument. Namespace uniquely identifies a callback in the form vendor/plugin/function.

API Usage

• createHooks()
• addAction( 'hookName', 'namespace', callback, priority )
• addFilter( 'hookName', 'namespace', callback, priority )
• removeAction( 'hookName', 'namespace' )
• removeFilter( 'hookName', 'namespace' )
• removeAllActions( 'hookName' )
• removeAllFilters( 'hookName' )
• doAction( 'hookName', arg1, arg2, moreArgs, finalArg )
• applyFilters( 'hookName', content, arg1, arg2, moreArgs, finalArg )
• doingAction( 'hookName' )
• doingFilter( 'hookName' )
• didAction( 'hookName' )
• didFilter( 'hookName' )
• hasAction( 'hookName', 'namespace' )
• hasFilter( 'hookName', 'namespace' )
• actions
• filters
• defaultHooks

Events on action/filter add or remove

Whenever an action or filter is added or removed, a matching hookAdded or hookRemoved action is triggered.

• hookAdded action is triggered when addFilter() or addAction() method is called, passing values for hookName, functionName, callback and priority.
• hookRemoved action is triggered when removeFilter() or removeAction() method is called, passing values for hookName and functionName.

The all hook

In non-minified builds developers can register a filter or action that will be called on all hooks, for example: addAction( 'all', 'namespace', callbackFunction );. Useful for debugging, the code supporting the all hook is stripped from the production code for performance reasons.

Contributing to this package

This is an individual package that's part of the Gutenberg project. The project is organized as a monorepo. It's made up of multiple self-contained software packages, each with a specific purpose. The packages in this monorepo are published to npm and used by WordPress as well as other software projects.

To find out more about contributing to this package or Gutenberg as a whole, please read the project's main contributor guide.