IntelliJ IDEA 2021.2 Help


With IntelliJ IDEA, you can develop modern web, mobile, and desktop applications with JavaScript and Node.js.

IntelliJ IDEA also supports React, Angular, Vue.js, and other frameworks and provides tight integration with various tools for web development.

JavaScript-aware coding assistance includes completion for keywords, labels, variables, parameters, and functions, error and syntax highlighting, formatting, numerous code inspections and quick-fixes, as well as common and JavaScript-specific refactoring. IntelliJ IDEA also integrates with JavaScript linters and the Flow type checker.

With IntelliJ IDEA built-in debugger, you can debug both your client-side and server-side code and even run JavaScript code snippets in the interactive debugger console. Note that IntelliJ IDEA supports debugging JavaScript only in Chrome or any other browser of the Chrome family. Learn more from Debug JavaScript in Chrome.

IntelliJ IDEA integrates with Jest, Karma, Protractor, Cucumber, and Mocha testing frameworks. IntelliJ IDEA supports running and debugging tests as well as navigation between tests and subjects or between a failed test and the fragment of code that caused the problem.

On this page you will find a short Getting Started Guide that will walk you step by step from creating a web application to debugging and testing it.

Before you start

Make sure the JavaScript and TypeScript plugin is enabled on the Settings/Preferences | Plugins page, tab Installed, see Managing plugins for details.

Creating a new application

  1. Select File | New | Project from the main menu or click the New Project button on the Welcome screen.

  2. In the New Project dialog, select Empty Project in the left-hand pane.

  3. In the right-hand pane, select Empty Project again and click Next.

  4. On the second page of the wizard, specify the project name and the path to the folder where the project-related files will be stored. Click Finish.

Starting with an existing JavaScript application

If you are going to continue developing an existing JavaScript application, open it in IntelliJ IDEA, choose the JavaScript version to use, and configure the libraries in it. Optionally download the required npm dependencies.

Open the application sources that are already on your machine

  • Click Open or Import on the Welcome screen or select File | Open from the main menu. In the dialog that opens, select the folder where your sources are stored.

Check out the application sources from your version control

  1. Click Get from VCS on the Welcome screen or select <Your_VCS> | Get from Version Control from the main menu.

    <Your_VCS> stands for the Version Control System with which your currently opened project is associated.

  2. In the invoked dialog, select your version control system from the list and specify the repository to check out the application sources from.

Choosing the JavaScript language version

To get reliable and efficient coding assistance, you need to specify the language version that will be used in all JavaScript files of your project by default.

  1. In the Settings/Preferences dialog Ctrl+Alt+S, go to Languages and Frameworks | JavaScript. The JavaScript page opens.

  2. From the list, choose one of the supported JavaScript language versions:

    • ECMAScript 5.1

    • ECMAScript 6+: This version adds support for the features introduced in ECMAScript 2015-2020 and for JSX syntax as well as some current proposals to the standard.

    • Flow: This version adds support for the Flow syntax.

Using multiple JavaScript versions

If you are working on an application that uses both ECMAScript 5.1 and a newer version of ECMAScript, the easiest way is to choose the highest language version for the whole project from the list on the JavaScript page.

  1. On the JavaScript page, click the Browse button next to the JavaScript language version list. The JavaScript Language Versions dialog opens.

  2. Click Add and in the dialog that opens select the folder where you need a custom language version. IntelliJ IDEA brings you back to the JavaScript Language Versions dialog where the selected folder is shown in the Path field.

  3. From the Language list, choose the language version for the files in the selected folder. In all the other JavaScript files in the project IntelliJ IDEA will use the version chosen on the JavaScript page.

    Choose language versions for separate folders

JSX syntax in JavaScript code

If you are using JSX syntax in your JavaScript code, enable ECMAScript 6+.

  • In the Settings/Preferences dialog Ctrl+Alt+S, go to Languages and Frameworks | JavaScript, and select ECMAScript 6+ from the JavaScript language version list.

  • To be warned when JSX syntax is used by mistake, open the Settings/Preferences dialog Ctrl+Alt+S, go to Editor | Inspections, and enable the React JSX syntax inspection under JavaScript and TypeScript | General node. Use the search field to locate the inspection.

    Enable the React JSX syntax inspection

    Optionally, configure the inspection severity and scope. Learn more from Code inspections.

Downloading project dependencies

If your application uses some tools, libraries, or frameworks, download the required packages. To manage your project dependencies, you can use npm, Yarn 1, or Yarn 2, see npm and Yarn for details.

Install a package in an empty project

  • In the embedded Terminal(Alt+F12), type:

    npm install <package name>.

If you already have a package.json file in your project

  • Right-click the package.json file in the editor or in the Project tool window and choose Run 'npm install' from the context menu.

  • Alternatively, run npm install in the Terminal Alt+F12.

Configuring code completion for project dependencies

To provide code completion for project dependencies, IntelliJ IDEA automatically creates a node_modules library. In IntelliJ IDEA, a library is a file or a set of files whose functions and methods are added to IntelliJ IDEA's internal knowledge in addition to the functions and methods that IntelliJ IDEA retrieves from the project code that you edit. See Configure JavaScript libraries and Code completion for details and examples.

Viewing parameter hints

Parameter hints show the names of parameters in methods and functions to make your code easier to read. By default, parameter hints are shown only for values that are literals or function expressions but not for named objects.

Parameter hints in JavaScript

Configure parameter hints

  1. Open the Settings/Preferences dialog Ctrl+Alt+S and go to Editor | Inlay Hints | JavaScript.

  2. Select Parameter hints from the list, make sure the Show parameter hints checkbox is selected, and then specify the context where you want parameter hints shown.

  3. For some methods and functions, IntelliJ IDEA does not show parameter hints in any context. Click Exclude list... to view these methods and functions, possibly enable parameter hints for them, or add new items to the list.

Auto-import in JavaScript

IntelliJ IDEA can generate import statements for modules, classes, components, and any other symbols that are exported. IntelliJ IDEA can add missing import statements on the fly, when you complete ES6 symbols or CommonJS modules. IntelliJ IDEA either decides on the style of the import statement itself or displays a popup where you can choose the style you need.

Add ES6 import statements

If you are importing a symbol from your project into a file that is a ES6 module or that already contains ES import statements, IntelliJ IDEA automatically inserts an ES6 import on symbol completion.

Add ES6 imports on code completion

For earlier JavaScript versions or when auto-import on completion is disabled, IntelliJ IDEA marks the symbol as unresolved and shows a tooltip with the suggested quick-fix:

Auto import with quick-fix: information tooltip

Alternatively, press Alt+Enter:

Auto import with quick-fix: suggestion list

If there's more than one possible source of import, IntelliJ IDEA shows a list of suggestions:

Auto import with quick-fix: multiple choices

Learn more from Choosing the JavaScript language version.

IntelliJ IDEA can also generate import statements for symbols defined in the project’s dependencies. Auto-import works for symbols from packages that contain TypeScript definition files (like in moment or redux) or sources written as ES modules.

If the current file already contains a ES6 import statement, IntelliJ IDEA inserts a new one also in the ES6 style.

Auto import from project dependencies

Add CommonJS (require) import statements

If you are importing a symbol from your project into a file that already is a CommonJS module (with a require statement or module.export), IntelliJ IDEA automatically inserts a CommonJS import on symbol completion.

Auto import with CommonJS import statement

Alternatively, position the caret at the symbol to import, press Alt+Enter, and select a quick-fix with the CommonJS (require) import style.

Quick fix: select import style

Configure auto import

  1. To automatically add ES6 import statements on code completion, open the Settings/Preferences dialog Ctrl+Alt+S, go to Editor | General | Auto Import, and select the Add ES6 imports on code completion checkbox in the TypeScript/JavaScript area.

  2. To configure the appearance of import statements, open the Settings/Preferences dialog Ctrl+Alt+S, go to Editor | Code Style | JavaScript, and use the controls in the Imports tab, see Imports tab for details.

Configure syntax highlighting

You can configure JavaScript-aware syntax highlighting according to your preferences and habits.

  1. In the Settings/Preferences dialog Ctrl+Alt+S, go to Editor | Color Scheme | JavaScript.

  2. Select the color scheme, accept the highlighting settings inherited from the defaults or customize them as described in Colors and fonts.

Run JavaScript in browser

  1. In the editor, open the HTML file with the JavaScript reference. This HTML file does not necessarily have to be the one that implements the starting page of the application.

  2. Do one of the following:
    • Choose View | Open in Browser from the main menu or press Alt+F2. Then select the desired browser from the list.

    • Hover your mouse pointer over the code to show the browser icons bar: the IntelliJ IDEA icon Chrome Firefox Safari Opera Internet Explorer Edge. Click the icon that indicates the desired browser.

Debugging JavaScript

IntelliJ IDEA provides a built-in debugger for your client-side JavaScript code that works with Chrome or any other browser of the Chrome family. With IntelliJ IDEA, you can debug JavaScript applications running on the built-in server, on an external server, or on a remote server. For details, see Debug JavaScript in Chrome.

Last modified: 26 July 2021