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# Migrate older jQuery code to jQuery 3.0+
#### NOTE: If you have not yet upgraded to 1.12.x or 2.2.x, first upgrade to them and use [jQuery Migrate 1.x](https://github.com/jquery/jquery-migrate/tree/1.x-stable#readme) to resolve any compatibility issues before using jQuery Migrate 3.0 and upgrading to jQuery 3.0.
This plugin can be used to warn about and/or restore APIs and behaviors that have been deprecated and/or removed as of jQuery version 3.0.
See the [warnings page](https://github.com/jquery/jquery-migrate/blob/master/warnings.md) for more information regarding messages the plugin generates.
For more information about the changes made in jQuery 3.0, see the [upgrade guide](http://jquery.com/upgrade-guide/3.0/) and [blog post](http://blog.jquery.com/FILL-THIS-IN-UPON-FINAL-RELEASE).
In your web page, load this plugin *after* the script tag for jQuery, for example:
```html
```
The jQuery Migrate 3.0 plugin should be used only with jQuery 3.x releases. It can identify potential upgrade issues via its JQMIGRATE console warnings.
## Download
### Development vs. Production versions
To make it easier to find and remove deprecated functionality, the development version of the plugin displays warnings on the browser's console. In browsers that don't support the console interface at all times such as IE9, no messages may be generated unless you include a debugging library such as [Firebug Lite](https://getfirebug.com/firebuglite) before including the jQuery Migrate plugin. Developers can also inspect the `jQuery.migrateWarnings` array to see what error messages have been generated.
All warnings generated by this plugin start with the string "JQMIGRATE". A list of the warnings you may see are in [warnings.md](https://github.com/jquery/jquery-migrate/blob/master/warnings.md).
### Development version
The development version provides console warning messages when deprecated and/or removed APIs are used. Use this version during development and debugging, and whenever you are reporting bugs to the jQuery team.
**Latest released development version:** This file is hosted on jQuery's CDN, and can be hotlinked if desired.
[https://code.jquery.com/jquery-migrate-3.0.0.js](https://code.jquery.com/jquery-migrate-3.0.0.js)
**Current work-in-progress build:** Although this file represents the most recent updates to the plugin, it may not have been thoroughly tested.
[https://code.jquery.com/jquery-migrate-git.js](https://code.jquery.com/jquery-migrate-git.js)
### Production version
The minified production file is compressed and does not generate console warnings. It will only generate a console log message upon loading, or if it detects and error such as an outdated version of jQuery that it does not support. Do not use this file for development or debugging, it will make your life miserable.
**Latest released production version:**
[https://code.jquery.com/jquery-migrate-3.0.0.min.js](https://code.jquery.com/jquery-migrate-3.0.0.min.js)
This file is hosted on jQuery's CDN, and can be hotlinked if desired.
**Current work-in-progress build:** Although this file represents the most recent updates to the plugin, it may not have been thoroughly tested. We do not recommend using this file on production sites since it may be unstable; use the released production version above.
[https://code.jquery.com/jquery-migrate-git.min.js](https://code.jquery.com/jquery-migrate-git.min.js)
## Migrate Plugin API
This plugin adds some properties to the `jQuery` object that can be used to programmatically control and examine its behavior:
`jQuery.migrateWarnings`: This property is an array of string warning messages that have been generated by the code on the page, in the order they were generated. Messages appear in the array only once, even if the condition has occurred multiple times, unless `jQuery.migrateReset()` is called.
`jQuery.migrateMute`: Set this property to `true` to prevent console warnings from being generated in the development version. The `jQuery.migrateWarnings` array is still maintained when this property is set, which allows programmatic inspection without console output.
`jQuery.migrateTrace`: Set this property to `false` if you want warnings but do not want stack traces to appear on the console.
`jQuery.migrateReset()`: This method clears the `jQuery.migrateWarnings` array and "forgets" the list of messages that have been seen already.
`jQuery.migrateVersion`: This string property indicates the version of Migrate in use.
## Reporting problems
Bugs that only occur when the jQuery Migrate plugin is used should be reported in the [jQuery Migrate Issue Tracker](https://github.com/jquery/jquery-migrate/issues) and should be accompanied by an executable test case that demonstrates the bug. The easiest way to do this is via an online test tool such as [jsFiddle.net](https://jsFiddle.net/) or [jsbin.com](https://jsbin.com).
Bugs in jQuery itself should be reported on the [jQuery Core bug tracker](https://bugs.jquery.com/) and again should be accompanied by a test case from [jsFiddle.net](https://jsFiddle.net/) or [jsbin.com](http://jsbin.com) so that we can reproduce the issue.
For other questions about the plugin that aren't bugs, ask on the [jQuery Forum](http://forum.jquery.com).
Build and run tests:
====================================================
## Build with `npm` commands
```sh
$ git clone git://github.com/jquery/jquery-migrate.git
$ cd jquery-migrate
$ npm install
$ npm run build
```
## Build with [`grunt`](http://gruntjs.com/)
```sh
$ git clone git://github.com/jquery/jquery-migrate.git
$ cd jquery-migrate
$ npm install
$ npm install -g grunt-cli
$ grunt build
```
### Run tests
```sh
$ npm test
```
### Or
```sh
$ grunt test
```