Html/JavaScript preload images

Question

I have a page with some img links. When the images are in the hover state, I change a background of a div inside my page. The javascript code is below:

function hover(element) {
  if(element.id=="first"){
      element.setAttribute('src', './images/first_active_2.png');
      back.style.backgroundImage = 'url(./images/1.png)';
      text.src = './images/text_first_active.png';
  }
  if(element.id=="second"){
      element.setAttribute('src', './images/second_active_2.png');
      back.style.backgroundImage = 'url(./images/3.png)';
      text.src = './images/text_second_active.png';
  }
}

function unhover(element) {
  if(element.id=="first"){
    element.setAttribute('src', './images/first_inactive_2.png');
    text.src = './images/text_first_inactive.png';
  }
  if(element.id=="second"){
    element.setAttribute('src', './images/second_inactive_2.png');
    text.src = './images/text_second_inactive.png';
  }
}

and the html code:

<div id="back"/>
  <a>
    <img id="first" src="images/first_inactive_2.png" onmouseover="hover(this);" onmouseout="unhover(this);" />
  </a>
  <a>
    <img id="second" src="images/second_inactive_2.png" onmouseover="hover(this);" onmouseout="unhover(this);"/>
  </a>

Everything is good, but the fact that sometimes the background image flickers. I think I have to preloade the two images/1.png, images/2.png, but I don't know how to do it properly. Is there a correct way to have the images not flickering?

This has been asked several times before. See, e.g., http://stackoverflow.com/q/7673843/1679849 — r3mainer, Jan 14 '14 at 08:57
Better use [CSS Sprites](http://stackoverflow.com/a/819395/1328300) — Uooo, Jan 14 '14 at 10:23

score 1 · Answer 1 · answered Jan 14 '14 at 09:01

1

var img = new Image(); img.src = "/path/to/image.jpg";

This could be in a window.load or dom:ready event somewhere and this way you could preload an image.

answered Jan 14 '14 at 09:01

Pranav

666
3
7

Marvin · Answer 2 · 2014-01-14T09:25:07.057

0

I had a similar problem a few weeks ago. You can preload an Image using 'onload' event:

var tmpNewImg = new Image();
tmpNewImg.onload = function () {
  var yourDiv = document.getElementById('picture');
  yourDiv.style.backgroundImage = 'url(' + this.src + ')';
}

tmpNewImg.src = '/your/background/image.jpg';

This helped for my problem. But I didn't test the code in this case.

edited Jan 14 '14 at 09:25

answered Jan 14 '14 at 09:08

Marvin

539
5
17

score 0 · Answer 3 · answered Jan 14 '14 at 09:08

Use css :hover and preload hover image in :after pseudo-element:

div {
    background: url(http://keddr.com/wp-content/uploads/2013/12/google.png);
    width:300px;
    height: 200px;
    background-size: 100% 100%;
}

div:after {
    content: '';
    font: 0/0 a;
}

div:hover,
div:after {
    background-image: url(http://hi-news.ru/wp-content/uploads/2013/11/0111.jpg);
}

Html/JavaScript preload images

3 Answers3