require-dollar-before-jquery-assignment.js

/**
 * Require a $ before variable names that are jquery assignments.
 *
 * Types: `Boolean` or `String`
 *
 * Values: `true` or `"ignoreProperties"`
 *
 * #### Example
 *
 * ```js
 * "requireDollarBeforejQueryAssignment": true
 * ```
 *
 * ##### Valid example for mode `true`
 *
 * ```js
 * var $x = $(".foo");
 * var y = {
 *   $x: $(".bar")
 * };
 * ```
 *
 * ##### Invalid example for mode `true`
 *
 * ```js
 * var x = $(".foo");
 * var y = {
 *   x: $(".bar")
 * };
 * ```
 *
 * ##### Valid example for mode `ignoreProperties`
 *
 * ```js
 * var $x = $(".foo");
 * var y = {
 *   x: $(".bar")
 * };
 * ```
 *
 * ##### Invalid example for mode `ignoreProperties`
 *
 * ```js
 * var x = $(".foo");
 * ```
 */

var assert = require('assert');

module.exports = function() {};

module.exports.prototype = {

    _ignoreProperties: false,

    configure: function(options) {
        assert(
            options === true || options === 'ignoreProperties',
            this.getOptionName() + ' option requires true or "ignoreProperties" value, or should be removed'
        );

        this._ignoreProperties = (options === 'ignoreProperties');
    },

    getOptionName: function() {
        return 'requireDollarBeforejQueryAssignment';
    },

    check: function(file, errors) {
        var ignoreProperties = this._ignoreProperties;

        file.iterateNodesByType(['VariableDeclarator', 'AssignmentExpression', 'ObjectExpression'], function(node) {
            var type = node.type;
            var left;
            var varName;
            var right;

            function checkIfVarNameShouldStartWithDollar(varName, left, right) {

                if (/^_?\$/.test(varName)) {
                    return;
                }

                if (!right || right.type !== 'CallExpression') {
                    return;
                }

                var nextToken = right.callee.firstChild;
                if (nextToken.value !== '$') {
                    return;
                }

                nextToken = file.getNextToken(nextToken);
                if (nextToken.value !== '(') {
                    return;
                }

                while (!(nextToken.type === 'Punctuator' && nextToken.value === ')')) {
                    nextToken = file.getNextToken(nextToken);
                }

                nextToken = file.getNextToken(nextToken);
                if (!nextToken || !(nextToken.type === 'Punctuator' && nextToken.value === '.')) {
                    errors.add(
                        'jQuery identifiers must start with a $',
                        left
                    );
                }
            }

            if (type === 'VariableDeclarator') {
                if (node.id.type === 'ObjectPattern' || node.id.type === 'ArrayPattern') {
                    return;
                }

                left = node.id;
                varName = left.name;
                right = node.init;
                checkIfVarNameShouldStartWithDollar(varName, left, right);
            } else if (ignoreProperties) {
                return;

            } else if (type === 'AssignmentExpression') {
                left = node.left;
                if (left.computed || left.type === 'ArrayPattern') {
                    return;
                }

                varName = left.name || left.property.name;
                right = node.right;
                checkIfVarNameShouldStartWithDollar(varName, left, right);
            } else {// type === 'ObjectExpression'
                var props = node.properties;

                if (!props) {
                    return;
                }

                props.forEach(function(prop) {
                    left = prop.key;

                    if (!left || !left.name) {
                        return;
                    }

                    varName = left.name;
                    right = prop.value;
                    checkIfVarNameShouldStartWithDollar(varName, left, right);
                });
            }

        });
    }
};