Webpack: ESLint jQuery $ Is Not Defined

When you enable ESLint in webpack, an error of http://eslint.org/docs/rules/no-undef '$' is not defined is shown when you try to use jQuery in your javascripts.

To solve this error, edit .eslintrc.js to add jquery: true for env.

module.exports = {  ...  env: {    browser: true,    // EDIT    jquery: true  },...}