JSFiddle - React, Tailwind, and code Playground

by Santosh Giridhara

HTML

<div id='displayResponse'></div>

JavaScript

// In this example the sample response should be
// {"data_sample":"data has not been modified"}
// and we will change it into
// {"data_sample":"woops! All data has gone!"}

/*---BEGIN HACK---------------------------------------------------------------*/

// here we will modify the response
function modifyResponse(response) {

    var original_response, modified_response;

    if (this.readyState === 4) {

        // we need to store the original response before any modifications
        // because the next step will erase everything it had
        original_response = response.target.responseText;

        // here we "kill" the response property of this request
        // and we set it to writable
        Object.defineProperty(this, "responseText", {writable: true});

        // now we can make our modifications and save them in our new property
        modified_response = original_response ?JSON.parse(b64DecodeUnicode(original_response)) : original_response;
        
        this.responseText = JSON.stringify(modified_response);

    }
}

// here we listen to all requests being opened
function openBypass(original_function) {

    return function(method, url, async) {

        // here we listen to the same request the "original" code made
        // before it can listen to it, this guarantees that
        // any response it receives will pass through our modifier
        // function before reaching the "original" code
        this.addEventListener("readystatechange", modifyResponse);

        // here we return everything original_function might
        // return so nothing breaks
        return original_function.apply(this, arguments);

    };

}

// here we override the default .open method so that
// we can listen and modify the request before the original function get its
XMLHttpRequest.prototype.open = openBypass(XMLHttpRequest.prototype.open);
// to see the original response just remove/comment the line above

/*---END...