no-primitive-constructors.js

/**
 * Copyright (c) 2015-present, Facebook, Inc.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @emails react-core
 */

'use strict';

module.exports = function(context) {
  function report(node, name, msg) {
    context.report(node, `Do not use the ${name} constructor. ${msg}`);
  }

  function check(node) {
    const name = node.callee.name;
    switch (name) {
      case 'Boolean':
        report(
          node,
          name,
          'To cast a value to a boolean, use double negation: !!value'
        );
        break;
      case 'String':
        report(
          node,
          name,
          'To cast a value to a string, concat it with the empty string ' +
            "(unless it's a symbol, which has different semantics): " +
            "'' + value"
        );
        break;
      case 'Number':
        report(
          node,
          name,
          'To cast a value to a number, use the plus operator: +value'
        );
        break;
    }
  }

  return {
    CallExpression: check,
    NewExpression: check,
  };
};