Basic Authentication Using JavaScript

After Spending quite a bit of time looking into this, i came up with the solution for this; In this solution i am not using the Basic authentication but instead went with the oAuth authentication protocol. But to use Basic authentication you should be able to specify this in the "setHeaderRequest" with minimal changes to the rest of the code example. I hope this will be able to help someone else in the future:

var token_ // variable will store the token
var userName = "clientID"; // app clientID
var passWord = "secretKey"; // app clientSecret
var caspioTokenUrl = "https://xxx123.caspio.com/oauth/token"; // Your application token endpoint  
var request = new XMLHttpRequest(); 

function getToken(url, clientID, clientSecret) {
    var key;           
    request.open("POST", url, true); 
    request.setRequestHeader("Content-type", "application/json");
    request.send("grant_type=client_credentials&client_id="+clientID+"&"+"client_secret="+clientSecret); // specify the credentials to receive the token on request
    request.onreadystatechange = function () {
        if (request.readyState == request.DONE) {
            var response = request.responseText;
            var obj = JSON.parse(response); 
            key = obj.access_token; //store the value of the accesstoken
            token_ = key; // store token in your global variable "token_" or you could simply return the value of the access token from the function
        }
    }
}
// Get the token
getToken(caspioTokenUrl, userName, passWord);

If you are using the Caspio REST API on some request it may be imperative that you to encode the paramaters for certain request to your endpoint; see the Caspio documentation on this issue;

NOTE: encodedParams is NOT used in this example but was used in my solution.

Now that you have the token stored from the token endpoint you should be able to successfully authenticate for subsequent request from the caspio resource endpoint for your application

function CallWebAPI() {
    var request_ = new XMLHttpRequest();        
    var encodedParams = encodeURIComponent(params);
    request_.open("GET", "https://xxx123.caspio.com/rest/v1/tables/", true);
    request_.setRequestHeader("Authorization", "Bearer "+ token_);
    request_.send();
    request_.onreadystatechange = function () {
        if (request_.readyState == 4 && request_.status == 200) {
            var response = request_.responseText;
            var obj = JSON.parse(response); 
            // handle data as needed... 

        }
    }
} 

This solution does only considers how to successfully make the authenticated request using the Caspio API in pure javascript. There are still many flaws i am sure...

Today we use Bearer token more often that Basic Authentication but if you want to have Basic Authentication first to get Bearer token then there is a couple ways:

const request = new XMLHttpRequest();
request.open('GET', url, false, username,password)
request.onreadystatechange = function() {
        // D some business logics here if you receive return
   if(request.readyState === 4 && request.status === 200) {
       console.log(request.responseText);
   }
}
request.send()

Full syntax is here

Second Approach using Ajax:

$.ajax
({
  type: "GET",
  url: "abc.xyz",
  dataType: 'json',
  async: false,
  username: "username",
  password: "password",
  data: '{ "key":"sample" }',
  success: function (){
    alert('Thanks for your up vote!');
  }
});

Hopefully, this provides you a hint where to start API calls with JS. In Frameworks like Angular, React, etc there are more powerful ways to make API call with Basic Authentication or Oauth Authentication. Just explore it.