[javascript] Basic authentication with fetch?

I want to write a simple basic authentication with fetch, but I keep getting a 401 error. It would be awesome if someone tells me what's wrong with the code:

let base64 = require('base-64');

let url = 'http://eu.httpbin.org/basic-auth/user/passwd';
let username = 'user';
let password = 'passwd';

let headers = new Headers();

//headers.append('Content-Type', 'text/json');
headers.append('Authorization', 'Basic' + base64.encode(username + ":" + password));

fetch(url, {method:'GET',
        headers: headers,
        //credentials: 'user:passwd'
       })
.then(response => response.json())
.then(json => console.log(json));
//.done();

function parseJSON(response) {
return response.json()
}

NODE USERS (REACT,EXPRESS) FOLLOW THESE STEPS

1. npm install base-64 --save
2. import { encode } from "base-64";

3.  const response = await fetch(URL, {
     method: 'post',
     headers: new Headers({
       'Authorization': 'Basic ' + encode(username + ":" + password),
       'Content-Type': 'application/json'
     }),
     body: JSON.stringify({
       "PassengerMobile": "xxxxxxxxxxxx",
       "Password": "xxxxxxx"
     })
   });
   const posts = await response.json();
   

4. Don't forget to define this whole function as async

This is not directly related to the initial issue, but probably will help somebody.

I faced same issue when was trying to send similar request using domain account. So mine issue was in not escaped character in login name.

Bad example:

'ABC\username'

Good example:

'ABC\\username'

A simple example for copy-pasting into Chrome console:

fetch('https://example.com/path', {method:'GET', 
headers: {'Authorization': 'Basic ' + btoa('login:password')}})
.then(response => response.json())
.then(json => console.log(json));

You can also use btoa instead of base64.encode().

headers.set('Authorization', 'Basic ' + btoa(username + ":" + password));

If you have a backend server asking for the Basic Auth credentials before the app then this is sufficient, it will re-use that then:

fetch(url, {
  credentials: 'include',
}).then(...);

A solution without dependencies.

Node

headers.set('Authorization', 'Basic ' + Buffer.from(username + ":" + password).toString('base64'));

Browser

headers.set('Authorization', 'Basic ' + btoa(username + ":" + password));

I'll share a code which has Basic Auth Header form data request body,

let username = 'test-name';
let password = 'EbQZB37gbS2yEsfs';
let formdata = new FormData();
let headers = new Headers();


formdata.append('grant_type','password');
formdata.append('username','testname');
formdata.append('password','qawsedrf');

headers.append('Authorization', 'Basic ' + base64.encode(username + ":" + password));
fetch('https://www.example.com/token.php', {
 method: 'POST',
 headers: headers,
 body: formdata
}).then((response) => response.json())
.then((responseJson) => {
 console.log(responseJson);

 this.setState({
    data: responseJson
 })
  })
   .catch((error) => {
 console.error(error);
   });