### Install client-oauth2

Source: https://github.com/n8n-io/js-client-oauth2-extended/blob/master/README.md

Install the client-oauth2 library using npm.

```sh
npm install client-oauth2 --save
```

--------------------------------

### Implicit Grant: Get Token and Make Request

Source: https://github.com/n8n-io/js-client-oauth2-extended/blob/master/README.md

Use this for obtaining access tokens in browser-based applications. Redirect the user to get an authorization URI, then parse the response URI to get the token and make authenticated requests.

```javascript
window.oauth2Callback = function (uri) {
  githubAuth.token.getToken(uri)
    .then(function (user) {
      console.log(user) //=> { accessToken: '...', tokenType: 'bearer', ... }

      // Make a request to the github API for the current user.
      return popsicle.request(user.sign({
        method: 'get',
        url: 'https://api.github.com/user'
      })).then(function (res) {
        console.log(res) //=> { body: { ... }, status: 200, headers: { ... } }
      })
    })
}

// Open the page in a new window, then redirect back to a page that calls our global `oauth2Callback` function.
window.open(githubAuth.token.getUri())
```

--------------------------------

### Client Credentials Grant: Get Token

Source: https://github.com/n8n-io/js-client-oauth2-extended/blob/master/README.md

Use this when the client needs access to protected resources under its control. Get the access token for the application using client credentials.

```javascript
githubAuth.credentials.getToken()
  .then(function (user) {
    console.log(user) //=> { accessToken: '...', tokenType: 'bearer', ... }
  })
```

--------------------------------

### JWT Bearer Grant: Get Token

Source: https://github.com/n8n-io/js-client-oauth2-extended/blob/master/README.md

Obtain an access token by utilizing an existing trust relationship expressed through a JWT. Provide the JWT to the `getToken` method.

```javascript
githubAuth.jwt.getToken('eyJhbGciOiJFUzI1NiJ9.eyJpc3Mi[...omitted for brevity...].J9l-ZhwP[...omitted for brevity...]')
  .then(function (user) {
    console.log(user) //=> { accessToken: '...', tokenType: 'bearer', ... }
  })
```

--------------------------------

### Authorization Code Grant Flow - Get Token

Source: https://github.com/n8n-io/js-client-oauth2-extended/blob/master/README.md

Handle the callback from the authorization server, exchange the authorization code for an access token, and manage the user's session.

```javascript
app.get('/auth/github/callback', function (req, res) {
  githubAuth.code.getToken(req.originalUrl)
    .then(function (user) {
      console.log(user) //=> { accessToken: '...', tokenType: 'bearer', ... }

      // Refresh the current users access token.
      user.refresh().then(function (updatedUser) {
        console.log(updatedUser !== user) //=> true
        console.log(updatedUser.accessToken)
      })

      // Sign API requests on behalf of the current user.
      user.sign({
        method: 'get',
        url: 'http://example.com'
      })

      // We should store the token into a database.
      return res.send(user.accessToken)
    })
})
```

--------------------------------

### Resource Owner Password Credentials Grant: Get Token

Source: https://github.com/n8n-io/js-client-oauth2-extended/blob/master/README.md

Suitable for trusted clients like operating system applications. Make a direct request for the access token using the username and password.

```javascript
githubAuth.owner.getToken('blakeembrey', 'hunter2')
  .then(function (user) {
    console.log(user) //=> { accessToken: '...', tokenType: 'bearer', ... }
  })
```

--------------------------------

### Initialize GitHub OAuth Client

Source: https://github.com/n8n-io/js-client-oauth2-extended/blob/master/README.md

Create a new instance of the OAuth 2.0 client for GitHub authentication.

```javascript
var ClientOAuth2 = require('client-oauth2')

var githubAuth = new ClientOAuth2({
  clientId: 'abc',
  clientSecret: '123',
  accessTokenUri: 'https://github.com/login/oauth/access_token',
  authorizationUri: 'https://github.com/login/oauth/authorize',
  redirectUri: 'http://example.com/auth/github/callback',
  scopes: ['notifications', 'gist']
})
```

--------------------------------

### Create and Manage Access Token

Source: https://github.com/n8n-io/js-client-oauth2-extended/blob/master/README.md

Create a token instance, set its expiration, and refresh it. This is useful for managing user credentials after initial authentication.

```javascript
// Can also just pass the raw `data` object in place of an argument.
var token = githubAuth.createToken('access token', 'optional refresh token', 'optional token type', { data: 'raw user data' })

// Set the token TTL.
token.expiresIn(1234) // Seconds.
token.expiresIn(new Date('2016-11-08')) // Date.

// Refresh the users credentials and save the new access token and info.
token.refresh().then(storeNewToken)

// Sign a standard HTTP request object, updating the URL with the access token
// or adding authorization headers, depending on token type.
token.sign({
  method: 'get',
  url: 'https://api.github.com/users'
}) //=> { method, url, headers, ... }
```

--------------------------------

### Authorization Code Grant Flow - Redirect

Source: https://github.com/n8n-io/js-client-oauth2-extended/blob/master/README.md

Initiate the Authorization Code Grant flow by redirecting the user to the authorization server.

```javascript
var express = require('express')
var app = express()

app.get('/auth/github', function (req, res) {
  var uri = githubAuth.code.getUri()

  res.redirect(uri)
})
```

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