New rule: no-fx

In slim mode, $.fx is completely missing, so create a rule
for this (more generic that no-fx-interval, which exists as
that property is deprecated).

README.md

@@ -121,6 +121,7 @@ Where rules are included in the configs `recommended`, `slim`, `all` or `depreca
 * [`no-jquery/no-find`](docs/rules/no-find.md)
 * [`no-jquery/no-find-collection`](docs/rules/no-find-collection.md) `all`
 * [`no-jquery/no-find-util`](docs/rules/no-find-util.md) `all`
+* [`no-jquery/no-fx`](docs/rules/no-fx.md) `slim`
 * [`no-jquery/no-fx-interval`](docs/rules/no-fx-interval.md) `3.0`
 * [`no-jquery/no-global-eval`](docs/rules/no-global-eval.md) `all`
 * [`no-jquery/no-global-selector`](docs/rules/no-global-selector.md) ⚙️

docs/rules/no-fx.md

@@ -0,0 +1,30 @@
+[//]: # (This file is generated by eslint-docgen. Do not edit it directly.)
+
+# no-fx
+
+Disallows `$.fx`.
+
+📋 This rule is enabled in `plugin:no-jquery/slim`.
+
+## Rule details
+
+❌ Examples of **incorrect** code:
+```js
+$.fx;
+$.fx.interval;
+$.fx.off;
+$.fx.speeds.slow;
+$.fx.start();
+```
+
+✔️ Examples of **correct** code:
+```js
+fx;
+fx.interval;
+a.fx;
+```
+
+## Resources
+
+* [Rule source](/src/rules/no-fx.js)
+* [Test source](/tests/rules/no-fx.js)

src/index.js

@@ -39,6 +39,7 @@ module.exports = {
 		'no-find': require( './rules/no-find' ),
 		'no-find-collection': require( './rules/no-find-collection' ),
 		'no-find-util': require( './rules/no-find-util' ),
+		'no-fx': require( './rules/no-fx' ),
 		'no-fx-interval': require( './rules/no-fx-interval' ),
 		'no-global-eval': require( './rules/no-global-eval' ),
 		'no-global-selector': require( './rules/no-global-selector' ),
@@ -118,6 +119,7 @@ module.exports = {
 				'no-jquery/no-animate-toggle': 'error',
 				'no-jquery/no-fade': 'error',
 				'no-jquery/no-slide': 'error',
+				'no-jquery/no-fx': 'error',
 				// Ajax
 				'no-jquery/no-ajax': 'error',
 				'no-jquery/no-ajax-events': 'error',

src/rules/no-fx.js

@@ -0,0 +1,29 @@
+'use strict';
+
+const utils = require( '../utils.js' );
+
+module.exports = {
+	meta: {
+		type: 'suggestion',
+		docs: {
+			description: 'Disallows `$.fx`.'
+		},
+		schema: []
+	},
+
+	create: ( context ) => ( {
+		MemberExpression: ( node ) => {
+			if (
+				!utils.isjQueryConstructor( context, node.object.name ) ||
+					node.property.name !== 'fx'
+			) {
+				return;
+			}
+
+			context.report( {
+				node,
+				message: '$.fx is not allowed'
+			} );
+		}
+	} )
+};

tests/rules/no-fx.js

@@ -0,0 +1,33 @@
+'use strict';
+
+const rule = require( '../../src/rules/no-fx' );
+const RuleTester = require( '../../tools/rule-tester' );
+
+const error = '$.fx is not allowed';
+
+const ruleTester = new RuleTester();
+ruleTester.run( 'no-fx', rule, {
+	valid: [ 'fx', 'fx.interval', 'a.fx' ],
+	invalid: [
+		{
+			code: '$.fx',
+			errors: [ error ]
+		},
+		{
+			code: '$.fx.interval',
+			errors: [ error ]
+		},
+		{
+			code: '$.fx.off',
+			errors: [ error ]
+		},
+		{
+			code: '$.fx.speeds.slow',
+			errors: [ error ]
+		},
+		{
+			code: '$.fx.start()',
+			errors: [ error ]
+		}
+	]
+} );