no-class-state.js

'use strict';

const utils = require( '../utils.js' );

module.exports = {
	meta: {
		type: 'suggestion',
		docs: {
			description: 'Disallows ' + utils.jQueryCollectionLink( 'hasClass' ) +
			' and ' + utils.jQueryCollectionLink( 'toggleClass' ) +
			' to discourage querying the DOM for state information. ' +
			utils.jQueryCollectionLink( 'toggleClass' ) + ' may be used with a boolean argument as then it behaves like ' +
			utils.jQueryCollectionLink( 'addClass' ) + '/' + utils.jQueryCollectionLink( 'removeClass' ) + '.'
		},
		schema: []
	},

	create: ( context ) => ( {
		'CallExpression:exit': ( node ) => {
			if ( !(
				node.callee.type === 'MemberExpression' && (
					node.callee.property.name === 'hasClass' ||
						// toggleClass with one argument will check if the
						// class is already in the DOM before deciding what to do,
						// so it is equivalent to using hasClass.
						(
							node.callee.property.name === 'toggleClass' &&
							node.arguments.length === 1
						)
				)
			) ) {
				return;
			}

			if ( utils.isjQuery( context, node.callee ) ) {
				context.report( {
					node,
					message: 'Where possible, maintain application state in JS to avoid slower DOM queries'
				} );
			}
		}
	} )
};