Use basic authentication with jQuery and Ajax

Use jQuery's beforeSend callback to add an HTTP header with the authentication information:

beforeSend: function (xhr) {
    xhr.setRequestHeader ("Authorization", "Basic " + btoa(username + ":" + password));
},

---

How things change in a year. In addition to the header attribute in place of xhr.setRequestHeader, current jQuery (1.7.2+) includes a username and password attribute with the $.ajax call.

$.ajax
({
  type: "GET",
  url: "index1.php",
  dataType: 'json',
  username: username,
  password: password,
  data: '{ "comment" }',
  success: function (){
    alert('Thanks for your comment!'); 
  }
});

EDIT from comments and other answers: To be clear - in order to preemptively send authentication without a 401 Unauthorized response, instead of setRequestHeader (pre -1.7) use 'headers':

$.ajax
({
  type: "GET",
  url: "index1.php",
  dataType: 'json',
  headers: {
    "Authorization": "Basic " + btoa(USERNAME + ":" + PASSWORD)
  },
  data: '{ "comment" }',
  success: function (){
    alert('Thanks for your comment!'); 
  }
});

---

Use the beforeSend callback to add a HTTP header with the authentication information like so:

var username = $("input#username").val();
var password = $("input#password").val();  

function make_base_auth(user, password) {
  var tok = user + ':' + password;
  var hash = btoa(tok);
  return "Basic " + hash;
}
$.ajax
  ({
    type: "GET",
    url: "index1.php",
    dataType: 'json',
    async: false,
    data: '{}',
    beforeSend: function (xhr){ 
        xhr.setRequestHeader('Authorization', make_base_auth(username, password)); 
    },
    success: function (){
        alert('Thanks for your comment!'); 
    }
});

---

Or, simply use the headers property introduced in 1.5:

headers: {"Authorization": "Basic xxxx"}

Reference: jQuery Ajax API

---

The examples above are a bit confusing, and this is probably the best way:

$.ajaxSetup({
  headers: {
    'Authorization': "Basic " + btoa(USERNAME + ":" + PASSWORD)
  }
});

I took the above from a combination of Rico and Yossi's answer.

The btoa function Base64 encodes a string.

---

As others have suggested, you can set the username and password directly in the Ajax call:

$.ajax({
  username: username,
  password: password,
  // ... other parameters.
});

OR use the headers property if you would rather not store your credentials in plain text:

$.ajax({
  headers: {"Authorization": "Basic xxxx"},
  // ... other parameters.
});

Whichever way you send it, the server has to be very polite. For Apache, your .htaccess file should look something like this:

<LimitExcept OPTIONS>
    AuthUserFile /path/to/.htpasswd
    AuthType Basic
    AuthName "Whatever"
    Require valid-user
</LimitExcept>

Header always set Access-Control-Allow-Headers Authorization
Header always set Access-Control-Allow-Credentials true

SetEnvIf Origin "^(.*?)$" origin_is=$0
Header always set Access-Control-Allow-Origin %{origin_is}e env=origin_is

Explanation:

For some cross domain requests, the browser sends a preflight OPTIONS request that is missing your authentication headers. Wrap your authentication directives inside the LimitExcept tag to respond properly to the preflight.

Then send a few headers to tell the browser that it is allowed to authenticate, and the Access-Control-Allow-Origin to grant permission for the cross-site request.

In some cases, the * wildcard doesn't work as a value for Access-Control-Allow-Origin: You need to return the exact domain of the callee. Use SetEnvIf to capture this value.

---

Use the jQuery ajaxSetup function, that can set up default values for all ajax requests.

$.ajaxSetup({
  headers: {
    'Authorization': "Basic XXXXX"
  }
});

---

There are 3 ways to achieve this as shown below

Method 1:

var uName="abc";
var passwrd="pqr";

$.ajax({
    type: '{GET/POST}',
    url: '{urlpath}',
    headers: {
        "Authorization": "Basic " + btoa(uName+":"+passwrd);
    },
    success : function(data) {
      //Success block  
    },
   error: function (xhr,ajaxOptions,throwError){
    //Error block 
  },
});

Method 2:

var uName="abc";
var passwrd="pqr";

$.ajax({
    type: '{GET/POST}',
    url: '{urlpath}',
     beforeSend: function (xhr){ 
        xhr.setRequestHeader('Authorization', "Basic " + btoa(uName+":"+passwrd)); 
    },
    success : function(data) {
      //Success block 
   },
   error: function (xhr,ajaxOptions,throwError){
    //Error block 
  },
});

Method 3:

var uName="abc";
var passwrd="pqr";

$.ajax({
    type: '{GET/POST}',
    url: '{urlpath}',
    username:uName,
    password:passwrd, 
    success : function(data) {
    //Success block  
   },
    error: function (xhr,ajaxOptions,throwError){
    //Error block 
  },
});

---

JSONP does not work with basic authentication so the jQuery beforeSend callback won't work with JSONP/Script.

I managed to work around this limitation by adding the user and password to the request (e.g. user:pw@domain.tld). This works with pretty much any browser except Internet Explorer where authentication through URLs is not supported (the call will simply not be executed).

See http://support.microsoft.com/kb/834489.

---

According to SharkAlley answer it works with nginx too.

I was search for a solution to get data by jQuery from a server behind nginx and restricted by Base Auth. This works for me:

server {
    server_name example.com;

    location / {
        if ($request_method = OPTIONS ) {
            add_header Access-Control-Allow-Origin "*";
            add_header Access-Control-Allow-Methods "GET, OPTIONS";
            add_header Access-Control-Allow-Headers "Authorization";

            # Not necessary
            #            add_header Access-Control-Allow-Credentials "true";
            #            add_header Content-Length 0;
            #            add_header Content-Type text/plain;

            return 200;
        }

        auth_basic "Restricted";
        auth_basic_user_file /var/.htpasswd;

        proxy_pass http://127.0.0.1:8100;
    }
}

And the JavaScript code is:

var auth = btoa('username:password');
$.ajax({
    type: 'GET',
    url: 'http://example.com',
    headers: {
        "Authorization": "Basic " + auth
    },
    success : function(data) {
    },
});

Article that I find useful:

This topic's answers http://enable-cors.org/server_nginx.html http://blog.rogeriopvl.com/archives/nginx-and-the-http-options-method/

---

Let me show you and Apache alternative- IIS which is need it before start real JQuery Ajax authentication

If we have /secure/* path for example. We need to create web.config and to prohibited access. Only after before send applayed must be able to access it pages in /secure paths

<?xml version="1.0"?>
<configuration>
  <system.web>
    <!-- Anonymous users are denied access to this folder (and its subfolders) -->
    <authorization>
      <deny users="?" />
    </authorization>
  </system.web>
</configuration>



<security>
   <authentication>
      <anonymousAuthentication enabled="false" />
      <basicAuthentication enabled="true" />
   </authentication>
</security>

---