Code Editor: Improve types and options handling

[westonruter]

This is a follow-up to:

• Switch from Esprima to Espree for JavaScript linting in CodeMirror. #10806
• Upgrade CodeMirror to latest v5 #10778

To address:

• Fix TypeScript issues with code-editor.js.
• Address issue where linting runs twice when the editor is initialized. See Switch from Esprima to Espree for JavaScript linting in CodeMirror. #10806 (comment). See dd7579f.

This is closely related to Core-61175 which introduces PHPStan as the PR for this ticket introduces TypeScript, although currently constrained to apply to files related to the code editor. The pull request introduces TypeScript to help guide the refactor to how linting options are gathered so as to avoid the double-linting issue. Instead of initializing with the default options first and then supplying the WordPress options, now it gathers the WordPress options and supplies them into the code editor when it first initializes.

Additionally, the source files were re-organized to remove our CodeMirror extension code from confusingly being located in a vendor directory.

In subsequent PRs:

• Remove jQuery dependency
• Add TypeScript to precommit task and GHA workflow. See Core-64662.

Trac ticket: https://core.trac.wordpress.org/ticket/64661

Gemini Summary

This branch introduces comprehensive TypeScript static analysis for JavaScript files using JSDoc, modernizes several Code Editor components, and refines the build and organizational structure of CodeMirror extensions.

1. TypeScript Static Analysis & Type Safety

• Infrastructure: Introduced tsconfig.json configured for JS checking (checkJs: true) and strict mode (strict: true). Added a typecheck:js script to package.json to facilitate this analysis.
• Global Definitions: Created typings/globals.d.ts to provide type definitions for WordPress globals (wp), jQuery, _ (Underscore), Backbone, and HTMLHint.
• Enhanced Type Definitions:
  • Defined precise JSDoc typedefs in code-editor.js (e.g., CodeEditorInstance, LintingController) to replace generic types.
  • Integrated CodeMirror addon types (lint, show-hint) using triple-slash directives.
  • Eliminated almost all generic any usage in favor of specific intersection types and unions.
• Strict Checking: Resolved numerous strict-mode issues, including mandatory null checks for optional callbacks and properties.

2. Code Modernization & Refactoring

• code-editor.js:
  • Modernized variable declarations using const and let.
  • Updated deprecated APIs: replaced event.keyCode with event.key and substr() with slice().
  • Adopted native DOM APIs where appropriate (classList, Node.contains).
  • Standardized code style with trailing commas in multi-line object literals.
• htmlhint-kses.js:
  • Refactored to modern ES syntax (arrow functions, template literals, and for...of loops).
  • Formatted with Prettier for consistency with modern standards.

3. Organization & Build Process

• Source Reorganization: Moved WordPress-maintained CodeMirror extensions (htmlhint-kses.js, javascript-lint.js) from vendor/ to lib/ to distinguish them from third-party code.
• Deprecation: The fakejshint.js file has been documented as deprecated and moved to src/js/_enqueues/deprecated/.
• Redundancy Cleanup: Removed the redundant esprima.js source file; the build now correctly sources it from the npm package.
• Linter Optimization:
  • Resolved a double-linting bug during initialization by centralizing option construction.
  • Removed obsolete nested options.options for linting, following modern CodeMirror standards.
• ESLint Alignment: Added a local .eslintrc.json in lib/codemirror/ to correctly signal ES module parsing for javascript-lint.js.

4. Dependencies

• Added @types packages for jquery, codemirror, underscore, espree, and htmlhint as devDependencies to support the static analysis effort.

All changes have been verified via npm run typecheck:js and npx grunt jshint:core.

Fixed PhpStorm Inspections

Use of AI Tools

I used Gemini CLI for granular commits, each of which I reviewed.

---

This Pull Request is for code review only. Please keep all other discussion in the Trac ticket. Do not merge this Pull Request. See GitHub Pull Requests for Code Review in the Core Handbook for more details.

[github-actions]

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[sirreal]

I've left some feedback mostly around the TypeScript setup. If you'd like, I'm happy to work on adjustments and push changes.

Frankly, I'd like to start using TypeScript syntax directly for these files that are already being compiled/bundled where we're adding a lot of type information. Whether a file is TypeScript or not could also serve as the condition for whether to check types.

[sirreal]

Here's the file diff between fdafcd3
and 5f54c0b. No obvious issues in the diff 👍

diff --git o/src/js/_enqueues/vendor/codemirror/htmlhint-kses.js w/src/js/_enqueues/lib/codemirror/htmlhint-kses.js
index 1aa7ffbd08..e08c4c0f5b 100644
--- o/src/js/_enqueues/vendor/codemirror/htmlhint-kses.js
+++ w/src/js/_enqueues/lib/codemirror/htmlhint-kses.js
@@ -1,30 +1,47 @@
 /* global HTMLHint */
-/* eslint no-magic-numbers: ["error", { "ignore": [0, 1] }] */
-HTMLHint.addRule({
+/* eslint no-magic-numbers: ["error", { "ignore": [1] }] */
+HTMLHint.addRule( {
 	id: 'kses',
 	description: 'Element or attribute cannot be used.',
-	init: function( parser, reporter, options ) {
+
+	/**
+	 * Initialize.
+	 *
+	 * @this {import('htmlhint/types').Rule}
+	 * @param {import('htmlhint').HTMLParser} parser - Parser.
+	 * @param {import('htmlhint').Reporter} reporter - Reporter.
+	 * @param {Record<string, Record<string, boolean>>} options - KSES options.
+	 * @return {void}
+	 */
+	init: function ( parser, reporter, options ) {
 		'use strict';
 
-		var self = this;
-		parser.addListener( 'tagstart', function( event ) {
-			var attr, col, attrName, allowedAttributes, i, len, tagName;
-
-			tagName = event.tagName.toLowerCase();
+		parser.addListener( 'tagstart', ( event ) => {
+			const tagName = event.tagName.toLowerCase();
 			if ( ! options[ tagName ] ) {
-				reporter.error( 'Tag <' + event.tagName + '> is not allowed.', event.line, event.col, self, event.raw );
+				reporter.error(
+					`Tag <${ event.tagName }> is not allowed.`,
+					event.line,
+					event.col,
+					this,
+					event.raw
+				);
 				return;
 			}
 
-			allowedAttributes = options[ tagName ];
-			col = event.col + event.tagName.length + 1;
-			for ( i = 0, len = event.attrs.length; i < len; i++ ) {
-				attr = event.attrs[ i ];
-				attrName = attr.name.toLowerCase();
-				if ( ! allowedAttributes[ attrName ] ) {
-					reporter.error( 'Tag attribute [' + attr.raw + ' ] is not allowed.', event.line, col + attr.index, self, attr.raw );
+			const allowedAttributes = options[ tagName ];
+			const column = event.col + event.tagName.length + 1;
+			for ( const attribute of event.attrs ) {
+				if ( ! allowedAttributes[ attribute.name.toLowerCase() ] ) {
+					reporter.error(
+						`Tag attribute [${ attribute.raw }] is not allowed.`,
+						event.line,
+						column + attribute.index,
+						this,
+						attribute.raw
+					);
 				}
 			}
-		});
-	}
-});
+		} );
+	},
+} );

[westonruter]

@sirreal:

I've left some feedback mostly around the TypeScript setup. If you'd like, I'm happy to work on adjustments and push changes.

Please do! Please amend as you see fit. I'm definitely not a TypeScript expert, so your expertise is much appreciated.

Frankly, I'd like to start using TypeScript syntax directly for these files that are already being compiled/bundled where we're adding a lot of type information.

That sounds good to me. I think in this PR that would mean we could turn src/js/_enqueues/lib/codemirror/javascript-lint.js and tools/vendors/codemirror-entry.js into TypeScript files. The other JS files, namely src/js/_enqueues/lib/codemirror/htmlhint-kses.js and src/js/_enqueues/wp/code-editor.js I think should remain as JS since they should be able to be run directly in the browser. (For example, I symlink them to src/wp-includes to avoid having to run a build when I make changes, although I'm willing to concede if this is just me.)

Whether a file is TypeScript or not could also serve as the condition for whether to check types.

There is a lot of type information added to code-editor.js though, so we should be sure to add that as an allow-list of JS files that we also start type-checking. I really would like to start incrementally adding more and more of the core JS files to beying type-checked as well.

[sirreal]

I've pushed several smaller changes mostly to adjust the TypeScript project configuration.

This seems ready. Thanks!

[sirreal]

The typcheck:js script doesn't run on CI, does it? That would be a good follow-up.

[westonruter]

Thank you!

The typcheck:js script doesn't run on CI, does it? That would be a good follow-up.

Yes, that is what Core-64662 for.

[westonruter]

@sirreal This change seems like it should be undone. In fact, a jQuery object is expected to be able to be passed in here:

wordpress-develop/src/js/_enqueues/wp/theme-plugin-editor.js

Line 417 in a58028d

editor = wp.codeEditor.initialize( $( '#newcontent' ), codeEditorSettings );

[westonruter]

Reverted in 5192ff9

[sirreal]

That's fine. This was flagged as an error for me when I tried tsgo, but the stable tsc does not complain.

[sirreal]

I pushed ed9f7b0 that I believe corrects the jQuery types and this type.

[github-actions]

The following accounts have interacted with this PR and/or linked issues. I will continue to update these lists as activity occurs. You can also manually ask me to refresh this list by adding the props-bot label.

Core Committers: Use this line as a base for the props when committing in SVN:

Props westonruter, jonsurrell, justlevine.

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[github-actions]

A commit was made that fixes the Trac ticket referenced in the description of this pull request.

SVN changeset: 61800
GitHub commit: b6c1bb7

This PR will be closed, but please confirm the accuracy of this and reopen if there is more work to be done.

[westonruter]

The typcheck:js script doesn't run on CI, does it? That would be a good follow-up.

Ready for review: #11131