JavaScript

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

CLion supports JavaScript and TypeScript programming languages, React and Angular frameworks and provides tight integration with various tools for web development.

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.

Creating a new application

Select File | New Project from the main menu or click Create New Project on the Welcome screen. The New Project dialog opens.
In the left-hand pane, choose one of the following options:
- Web Starter Kit
- Bootstrap
- Foundation
- React App
- React Native
In the right-hand pane, specify the path to the folder where the project-related files will be stored, and the version of the project template. Click Create.

Starting with an existing JavaScript application

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

To open the application sources that are already on your machine

Click Open 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.

To check out the application sources from your version control

Click Check out from Version Control on the Welcome screen or select VCS | Check out from Version Control from the main menu.
Select your version control system from the list.
In the VCS-specific dialog that opens, type your credentials and 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 application by default.

In the Settings/Preferences dialog (Ctrl+Alt+S), go to Languages and Frameworks | JavaScript. The JavaScript page opens.
From the list, choose one of the supported JavaScript language versions:
- ECMAScript 3
- ECMAScript 5.1
- JavaScript 1.8.5
- ECMAScript 6: This version adds support for the features introduced in ECMAScript 2015-2017 as well as some current proposals to the standard.
- React JSX: This version adds support for the JSX syntax on top of ECMAScript 6
- 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, or JSX, or Flow, the easiest way is to choose the highest language version for the whole project from the list on the JavaScript page. For example, if you use ES5.1 and JSX, enable JSX (since it is a superset of ES5.1 and ES6).

To configure different JavaScript language versions for different folders

On the JavaScript page, click next to the JavaScript language version list. The JavaScript Language Versions dialog opens.
Click and in the dialog that opens select the folder where you need a custom language version. CLion brings you back to the JavaScript Language Versions dialog where the selected folder is shown in the Path field.
From the Language list, choose the language version for the files in the selected folder. In all the other JavaScript files in the project CLion will use the version chosen on the JavaScript page.

Downloading npm dependencies

Make sure you have Node.js on your computer. If your application uses some tools, libraries, or frameworks, download the required packages.

To 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.

Configuring code completion for project dependencies

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

To configure parameter hints

In the Settings/Preferences dialog (Ctrl+Alt+S), go to Editor | General | Appearance. The Appearance page opens.
Click Configure next to the Show parameter name hint checkbox (the checkbox is selected by default).
In the Configure Parameter Name Hints dialog that opens, select the Show name for all arguments checkbox in the Options area.

Auto import in JavaScript

CLion can generate import statements for modules, classes, components, and any other symbols that are exported. If you are using ES6 in your project, CLion can add missing import statements on the fly, when you complete ES6 symbols.

For earlier JavaScript versions or wheauto-importrt on completion is disabled, CLion marks the symbol as unresolved and shows a tooltip:

On pressing Alt+Enter, CLion displays the suggested quick-fix:

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

To add ES6 import statements on code completion

In the Settings/Preferences dialog (Ctrl+Alt+S), go to Editor | General | Auto-import. The Auto Import page opens.
In the TypeScript/JavaScript area, select the Add ES6 imports on code completion checkbox.

CLion 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.

Configuring syntax highlighting

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

In the Settings/Preferences dialog (Ctrl+Alt+S), go to Editor | Color Scheme | JavaScript.
Select the color scheme, accept the highlighting settings inherited from defaults or customize them as described in Configuring Colors and Fonts.

Running JavaScript in browser

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.
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: Click the icon that indicates the desired browser.

Debugging JavaScript

CLion provides a built-in debugger for your client-side JavaScript code that works with Chrome.
You can also debug your client-side JavaScript in Firefox, version 36 and higher. However it is strongly recommended that you use Chrome or any other browser of the Chrome family. With CLion, you can debug JavaScript applications running on the built-in server, on an external server, or on a remote server. For details, see Debugging JavaScript in Chrome and Debugging JavaScript in Firefox.

Last modified: 24 July 2019