example.js

function makeRequest(url) {
    httpRequest = new XMLHttpRequest();
    if (!httpRequest) {
        displayErrorMsg('Sorry, there was a problem making the request!');
        return false;
    }
    httpRequest.onreadystatechange = receiveRequest;
    httpRequest.open('GET', url);
    httpRequest.send();
}

function receiveRequest() {
    if (httpRequest.readyState === XMLHttpRequest.DONE) {
        if (httpRequest.status === 200) {
            data = JSON.parse(httpRequest.response);
            console.log(data);
        } else {
            displayErrorMsg('Sorry, there was a problem with the request response!');
        }
    }
}

window.onload = makeRequest('http://api.giphy.com/v1/gifs/search?q=dog&limit=20&api_key=dc6zaTOxFJmzC');