github_example.js

window.addEventListener('load', function() {
  var githubBtn = document.getElementById('github');
  var otherBtn = document.getElementById('other');

  otherBtn.addEventListener('click', function() {
    getUrl('http://api.giphy.com/v1/gifs/random?api_key=dc6zaTOxFJmzC&tag=robots');
  });

  githubBtn.addEventListener('click', function() {
    getUrl('https://api.github.com/users/bwiggs');
  });

  function getUrl(url) {
    var xhr = new XMLHttpRequest();
    xhr.onreadystatechange = handleXHR;
    xhr.open('GET', url);
    xhr.send();
  }

  function handleXHR() {
    if(this.readyState === XMLHttpRequest.DONE) {
      switch(this.status) {
        case 200:
          console.log(this.responseText);
          break;
        default:
          console.log(this.status, 'error');
      }
    }
  }
});