It's a configuration file to assist your editor's Language Server Protocol (LSP) with the JavaScript usage in your project folder.

While it appears this has originated from Visual Studio Code, any editor using LSP will make use of file jsconfig.json, including Visual Studio Code, Sublime Text and so on.

It's most commonly used to include/exclude folders in your intellisense (which nowadays most editors use LSP), and map aliases in your source code to certain folders.

{
  "compilerOptions": {
    "baseUrl": ".",
    "paths": {
      "$libs": ["src/libs"],
      "$libs/*": ["src/libs/*"],
    }
  },
  "include": ["src/**/*.d.ts", "src/**/*.js", "src/**/*.svelte"],
  "exclude": ["node_modules", "**/node_modules", "dist"]
}

This file basically tells the language server to:

baseUrl

Use the . location as the project root (which is where file jsconfig.json) is.

paths

It means $libs in your source code points to /src/libs. This is useful if your editor relies on LSP to locate the files. When you initiate go to file it will go to the right place.

include

It means to include all folders and files ending with those extensions in providing you with file search, code completion.

exclude

It means to exclude everything inside node_modules and dist folder. For instance, you don't want the compiled bundle to appear in search results when you are searching for symbols or variables.

Remarks

In other words, you can consider the jsconfig.json file a bit like the .gitignore file, but for your editor's language server use only.

But keep in mind, if you are going to be using jsconfig.json to map aliases, you would need to do additional configuration to your module bundler, and update your eslint config, that is, if you use ESLint.

For instance, in a Node.js / CommonJS environment, you would need to tell your Node.js what $libs is. There are many ways to do so, but these days people mostly use module-alias.

This is definitely specific to Visual Studio Code.

The presence of jsconfig.json file in a directory indicates that the directory is the root of a JavaScript Project. The jsconfig.json file specifies the root files and the options for the features provided by the JavaScript language service.

Check more details in jsconfig.json.

You don't need this file when deploy it on AWS or Heroku. Basically, you can exclude this from your commit if you are using a Git repository, i.e., add jsconfig.json in your .gitignore file. This will make your project IDE-independent.

As other answers have noted, this protocol originated from Visual Studio Code - but has been adopted by many frameworks to work at compile-time:

Front-end

Front-end frameworks that support jsconfig.json and tsconfig.json:

• Create React App (see Importing a Component)
• Next.js (see Using baseUrl in jsconfig.json is not working with Next.js)

Back-end

Back-end Node.js support for jsconfig.json/tsconfig.json:

• module-alias