Hooks

Introduction

Cordova Hooks represent special scripts which could be added by application and plugin developers or even by your own build system to customize cordova commands.

Cordova hooks allow you to perform special activities around cordova commands. For example, you may have a custom tool that checks for code formatting in your javascript file. And, you would like to run this tool before every build. In such a case, you could use a 'before_build' hook and instruct the cordova run time to run the custom tool to be invoked before every build.

Hooks might be related to your application activities such as before_build, after_build, etc. Or, they might be related to the plugins of your application. For example, hooks such as before_plugin_add, after_plugin_add, etc applies to plugin related activities. These hooks can be associated with all plugins within your application or be specific to only one plugin.

Cordova supports the following hook types:

Hook Type	Associated Cordova Commands	Description
before_platform_add	cordova platform add	To be executed before and after adding a platform.
after_platform_add
before_platform_rm	cordova platform rm	To be executed before and after removing a platform.
after_platform_rm
before_platform_ls	cordova platform ls	To be executed before and after listing the installed and available platforms.
after_platform_ls
before_prepare	cordova prepare cordova platform add cordova build cordova run	To be executed before and after preparing your application.
after_prepare
before_compile	cordova compile cordova build	To be executed before and after compiling your application.
after_compile
before_deploy	cordova emulate cordova run	To be executed before deploying your application.
before_build	cordova build	To be executed before and after building your application.
after_build
before_emulate	cordova emulate	To be executed before and after emulating your application.
after_emulate
before_run	cordova run	To be executed before and after running your application.
after_run
before_serve	cordova serve	To be executed before and after serving your application.
after_serve
before_clean	cordova clean	To be executed before and after cleaning your application.
after_clean
before_plugin_add	cordova plugin add	To be executed before and after adding a plugin.
after_plugin_add
before_plugin_rm	cordova plugin rm	To be executed before and after removing a plugin.
after_plugin_rm
before_plugin_ls	cordova plugin ls	To be executed before and after listing the plugins in your application.
after_plugin_ls
before_plugin_install	cordova plugin add	To be executed before and after installing a plugin (to the platforms). Plugin hooks in plugin.xml are executed for a plugin being installed only
after_plugin_install
before_plugin_uninstall	cordova plugin rm	To be executed before uninstalling a plugin (from the platforms).Plugin hooks in plugin.xml are executed for a plugin being installed only

Ways to define hooks

Config.xml

Hooks could be defined in project's config.xml using <hook> elements, for example:

<hook type="before_build" src="scripts/appBeforeBuild.bat" />
<hook type="before_build" src="scripts/appBeforeBuild.js" />
<hook type="before_plugin_install" src="scripts/appBeforePluginInstall.js" />

<platform name="android">
    <hook type="before_build" src="scripts/android/appAndroidBeforeBuild.bat" />
    <hook type="before_build" src="scripts/android/appAndroidBeforeBuild.js" />
    <hook type="before_plugin_install" src="scripts/android/appAndroidBeforePluginInstall.js" />
    ...
</platform>

<platform name="windows">
    <hook type="before_build" src="scripts/windows/appWinBeforeBuild.bat" />
    <hook type="before_build" src="scripts/windows/appWinBeforeBuild.js" />
    <hook type="before_plugin_install" src="scripts/windows/appWinBeforePluginInstall.js" />
    ...
</platform>

Plugin hooks (plugin.xml)

As a plugin developer you can define hook scripts using <hook> elements in a plugin.xml like that:

<hook type="before_plugin_install" src="scripts/beforeInstall.js" />
<hook type="after_build" src="scripts/afterBuild.js" />

<platform name="android">
    <hook type="before_plugin_install" src="scripts/androidBeforeInstall.js" />
    <hook type="before_build" src="scripts/androidBeforeBuild.js" />
    ...
</platform>

before_plugin_install, after_plugin_install, before_plugin_uninstall plugin hooks will be fired exclusively for the plugin being installed/uninstalled.

Via /hooks directory (Deprecated)

To execute custom action when corresponding hook type is fired, use hook type as a name for a subfolder inside 'hooks' directory and place you script file here, for example:

# script file will be automatically executed after each build
hooks/after_build/after_build_custom_action.js

When using these hooks, they will always be run as executable files, not as loadable JavaScript modules.

Remember: Make your scripts executable in this case.

Note: this method is considered deprecated in favor of the hook elements in config.xml and plugin.xml.

Order of Hooks execution

Based on Hooks Definition

Hook scripts could be defined by adding them to the special predefined folder (/hooks) or via configuration files (config.xml and plugin.xml) and run serially in the following order:

• Application hooks from /hooks;
• Application hooks from config.xml;
• Plugin hooks from plugins/.../plugin.xml.

Based on the Internal order of execution

The internal order of execution of hooks is fixed.

Example 1 (cordova platform add)

If there are hooks associated with before_platform_add, after_platform_add, before_prepare, after_prepare, before_plugin_install and after_plugin_install (and assuming you have one plugin installed on your project), adding a new platform will execute the hooks in the following order:

before_platform_add
    before_prepare
    after_prepare
    before_plugin_install
    after_plugin_install
after_platform_add

Example 2 (cordova build)

If there are hooks associated with before_prepare, after_prepare, before_compile, after_compile, before_build and after_build - running a build command will execute the hooks in the following order:

before_build
    before_prepare
    after_prepare
    before_compile
    after_compile
after_build

Script Interface

Javascript

If you are writing hooks using Node.js you should use the following module definition:

module.exports = function(context) {
    ...
}

Here is an example that showcases the contents of the context object:

{
  // The type of hook being run
  hook: 'before_plugin_install',

  // Absolute path to the hook script that is currently executing
  scriptLocation: '/foo/scripts/appBeforePluginInstall.js',

  // The CLI command that lead to this hook being executed
  cmdLine: 'cordova plugin add plugin-withhooks',

  // The options associated with the current operation.
  // WARNING: The contents of this object vary among the different
  // operations and are currently not documented anywhere.
  opts: {
    projectRoot: '/foo',

    cordova: {
      platforms: ['android'],
      plugins: ['plugin-withhooks'],
      version: '0.21.7-dev'
    },

    // Information about the plugin currently operated on.
    // This object will only be passed to plugin hooks scripts.
    plugin: {
      id: 'plugin-withhooks',
      pluginInfo: { /* ... */ },
      platform: 'android',
      dir: '/foo/plugins/plugin-withhooks'
    }
  },

  // A reference to Cordova's API
  cordova: { /* ... */ }
}

You can also require additional Cordova modules in your script using context.requireCordovaModule in the following way:

const cordovaCommon = context.requireCordovaModule('cordova-common');

You can make your scripts asynchronous using Promises. Here is an example that just waits for a second and then prints the amount of milliseconds spent waiting:

module.exports = context => {
    return new Promise(resolve => {
        const start = Date.now();
        setTimeout(() => resolve(Date.now() - start), 1000);
    }).then(msWaited => {
        console.log(`${context.scriptLocation} waited ${msWaited} ms`);
    });
};

Note: new module loader script interface is used for the .js files defined via config.xml or plugin.xml only. For compatibility reasons hook files specified via /hooks folders are run via Node child_process spawn, see 'Non-javascript' section below.

Non-javascript

Non-javascript scripts are run via Node child_process spawn from the project's root directory and have the root directory passed as the first argument. All other options are passed to the script using environment variables:

Environment Variable Name	Description
CORDOVA_VERSION	The version of the Cordova-CLI.
CORDOVA_PLATFORMS	Comma separated list of platforms that the command applies to (e.g: android, ios).
CORDOVA_PLUGINS	Comma separated list of plugin IDs that the command applies to (e.g: cordova-plugin-file-transfer, cordova-plugin-file).
CORDOVA_HOOK	Path to the hook that is being executed.
CORDOVA_CMDLINE	The exact command-line arguments passed to cordova (e.g: cordova run ios --emulate).

If a script returns a non-zero exit code, then the parent cordova command will be aborted.

Note: we highly recommend writing your hooks using Node.js so that they are cross-platform, see Javascript section above.

Windows Quirks

If you are working on Windows, and your hook scripts aren't *.bat files, Cordova CLI will expect a shebang line as the first line of the script. This way it knows the interpreter it needs to use to launch the script. A shebang line for a Python script could look like this:

#!/usr/bin/env python

Sample Usage

This sample demonstrates Cordova hooks usage to trace to the console output the size of generated .apk file for Android platform.

Create blank Cordova app and add the following definition to config.xml to tell Cordova to run afterBuild.js script after each platform build.

<hook type="after_build" src="scripts/afterBuild.js" />

Create scripts/afterBuild.js file and add the following implementation. We use async version of fs.stat method to demonstrate how async functions can be used in hooks.

const fs = require('fs');
const util = require('util');
const stat = util.promisify(fs.stat);

module.exports = function(ctx) {
    // Make sure android platform is part of build
    if (!ctx.opts.platforms.includes('android')) return;

    const platformRoot = path.join(ctx.opts.projectRoot, 'platforms/android');
    const apkFileLocation = path.join(platformRoot, 'build/outputs/apk/android-debug.apk');

    return stat(apkFileLocation).then(stats => {
      console.log(`Size of ${apkFileLocation} is ${stats.size} bytes`);
    });
};

Parameter ctx in example above is passed by Cordova and represents execution context such as script full path, target platform, command-line arguments, etc and also exposes additional helper functionality. See Script Interface section above for more details.

You can now add android platform and execute build.

cordova platform add android
..
cordova build
..
Size of path\to\app\platforms\android\build\outputs\apk\android-debug.apk is 1821193 bytes

More good usage examples could be found in Three Hooks Your Cordova Phone Gap Project needs