The themes outlined for WordPress 4.9 are “editing code, managing plugins and themes, a user-centric way to customize a site, and polishing some recently added features over this last year.” Within the themes of editing code and polishing recent features, we’re improving the code editing functionality in the Customizer Tool built into WordPress core that hooks into most modern themes. You can use it to preview and modify many of your site’s appearance settings.’s Additional CSS feature, the Custom HTML widget, and the Plugin A plugin is a piece of software containing a group of functions that can be added to a WordPress website. They can extend functionality or add new features to your WordPress websites. WordPress plugins are written in the PHP programming language and integrate seamlessly with WordPress. These can be free in the WordPress.org Plugin Directory https://wordpress.org/plugins/ or can be cost-based plugin from a third-party and Theme file editors. We included these improvements to code editing among the 4.9 goals and this release is packed with them.
CodeMirror: Syntax Highlighting, Linting, and Auto-completion
The most visible and drastic improvement to code editing in 4.9 is that there is now an actual code editing control rather than just a textarea input. If you’ve been using WordPress for a long time (over 8 years), this may sound like déjà vu. Syntax highlighting for the theme and plugin editors was originally introduced in WordPress 2.8 (#9173) but it was removed shortly after in 2.8.1 due to browser compatibility problems with the “CodePress” library (no relation to WordPress). So in the 8 years since the feature was re-proposed in #12423, after considering a slew of code editor libraries, we decided on incorporating CodeMirror:
CodeMirror is a versatile text editor implemented in JavaScript JavaScript or JS is an object-oriented computer programming language commonly used to create interactive effects within web browsers. WordPress makes extensive use of JS for a better user experience. While PHP is executed on the server, JS executes within a user’s browser. https://www.javascript.com/. for the browser. It is specialized for editing code, and comes with a number of language modes and add-ons that implement more advanced editing functionality. ¶ A rich programming API An API or Application Programming Interface is a software intermediary that allows programs to interact with each other and share data in limited, clearly defined ways. and a CSS Cascading Style Sheets. theming system are available for customizing CodeMirror to fit your application, and extending it with new functionality.
You have probably already used this CodeMirror library a lot online, since it powers the editors in many familiar products and services including Brackets.io, Bitbucket, Chrome’s DevTools, Codepen, Firefox Developer Tools, GitHub GitHub is a website that offers online implementation of git repositories that can easily be shared, copied and modified by other developers. Public repositories are free to host, private repositories require a paid subscription. GitHub introduced the concept of the ‘pull request’ where code changes done in branches by contributors can be reviewed and discussed before being merged be the repository owner. https://github.com/, and JSFiddle, among many others. In the WordPress world specifically CodeMirror is also very familiar. Jetpack switched from ACE to CodeMirror in 2013 for its Custom CSS module, and there are close to 100 search results for CodeMirror on the plugin directory. Many of them should be updated to re-use CodeMirror as bundled with core Core is the set of software required to run WordPress. The Core Development Team builds WordPress. as well. See below for some details on how to do that.
The syntax highlighting abilities of CodeMirror can help authors catch many mistakes visually while writing code, as the color coding can quickly clue in that something isn’t right. In addition to color coding, WordPress also enables by default the add-ons which will auto-close brackets and tags, and then also highlight matching braces and tags which have already been written.
CodeMirror also supports linting to actually add explicit error checking beyond just stylistic helps. WordPress is initially bundling the following linters: CSSLint, JSHint, HTMLHint, and JSONLint. See #41873 for adding a PHP The web scripting language in which WordPress is primarily architected. WordPress requires PHP 7.4 or higher linter as well, though as described below, the theme and plugin editors have a more robust means of checking for PHP errors by running the code on the server itself. The linters will report either errors or warnings with your code:
