How to use jQuery with TypeScript

I am trying

$(function(){ 
    alert('Hello'); 
});

Its showing this error in Visual Studio: (TS) Cannot find name '$'.. How can I use jQuery with TypeScript ?

Most likely you need to download and include the TypeScript declaration file for jQuery—jquery.d.ts—in your project.

Option 1: Install the @types package (Recommended for TS 2.0+)

In the same folder as your package.json file, run the following command:

npm install --save-dev @types/jquery

Then the compiler will resolve the definitions for jquery automatically.

Option 2: Download Manually (Not Recommended)

Download it here.

Option 3: Using Typings (Pre TS 2.0)

If you're using typings then you can include it this way:

// 1. Install typings
npm install typings -g
// 2. Download jquery.d.ts (run this command in the root dir of your project)
typings install dt~jquery --global --save

After setting up the definition file, import the alias ($) in the desired TypeScript file to use it as you normally would.

import $ from "jquery";
// or
import $ = require("jquery");

You may need to compile with --allowSyntheticDefaultImports—add "allowSyntheticDefaultImports": true in tsconfig.json.

Also Install the Package?

If you don't have jquery installed, you probably want to install it as a dependency via npm (but this is not always the case):

npm install --save jquery

In my case I had to do this

npm install @types/jquery --save-dev // install jquery type as dev dependency so TS can compile properly
npm install jquery --save // save jquery as a dependency

Then in the script file A.ts

import * as $ from "jquery";
... jquery code ...

FOR Visual Studio Code

What works for me is to make sure I do the standard JQuery library loading via a < script > tag in the index.html.

Run

npm install --save @types/jquery

Now the JQuery $ functions are available in all .ts files, no need of any other imports.

For Angular CLI V2+

npm install jquery --save
npm install @types/jquery --save

Make sure jquery has an entry in angular.json -> scripts

...
    "scripts": [
        "node_modules/jquery/dist/jquery.min.js"
    ]
...

Go to tsconfig.app.json and add an entry in "types"

{
    "extends": "../tsconfig.json",
    "compilerOptions": {
        "outDir": "../out-tsc/app",
        "types": ["jquery","bootstrap","signalr"]
    },
    "exclude": [
        "test.ts",
        "**/*.spec.ts"
    ]
}