Cacher is the code snippet organizer for pro developers

var myImage = document.querySelector('img');

myImage.onclick = function() {
    var mySrc = myImage.getAttribute('src');
    if(mySrc === 'images/firefox-icon.png') {
      myImage.setAttribute ('src','images/firefox2.png');
    } else {
      myImage.setAttribute ('src','images/firefox-icon.png');
    }
}

document.querySelector('html').onclick = function() {
    alert('Hello!!');
}

//is equivalent to

var myHTML = document.querySelector('html');
myHTML.onclick = function() {};