How to display loading dialog when someone clicks a specific link?

Question

I do have an URL which opens a webpage which is very slow to load and I have no control over it.

I do want to display a loading dialog when someone clicks this URL or to

Answer 1

Although ajax would be more elegant, it's possible. You have to intercept the navigation by preventing the default event, then force an update to the UI, then change the location to the destination url. Something like this:

$('#mylink').click(function(e) {
    e.preventDefault();
    var url = this.href;
    // Update the UI here
    setTimeout(function() {
        // This is a trick to force a repaint
        window.location.href = url;
    },0);
});

Answer 2

If you also need an animation, it becomes a complicated matter as browsers behave very differently. Some stop all GIF animations when a new page starts loading. Basically it comes down to something like this if you have jQuery and download the spin.js library.

See working solution here:

http://jsfiddle.net/7aJyP/

<style>
#loading {
    display:none;
    position:absolute;
    left:0;
    top:0;
    z-index:1000;
    width:100%;
    height:100%;
    min-height:100%;
    background:#000;
    opacity:0.8;
    text-align:center;
    color:#fff;
}

#loading_anim {
    position:absolute;
    left:50%;
    top:50%;
    z-index:1010;
}
</style>



<div id="loading"><div id="loading_anim"></div></div>

<a href="http://pangoo.it" class="mylinkclass withanimation">link</a>



<script>

$(function () {
    $(".withanimation").click(function(e) {
        e.preventDefault();
        $("#loading").show();

        var url=$(this).attr("href");

        setTimeout(function() {
            setTimeout(function() {showSpinner();},30);
            window.location=url;
        },0);

   });
});

function showSpinner() {
    var opts = {
      lines: 15, // The number of lines to draw
      length: 3, // The length of each line
      width: 4, // The line thickness
      radius: 30, // The radius of the inner circle
      rotate: 0, // The rotation offset
      color: '#fff', // #rgb or #rrggbb
      speed: 2, // Rounds per second
      trail: 70, // Afterglow percentage
      shadow: false, // Whether to render a shadow
      hwaccel: false, // Whether to use hardware acceleration
      className: 'spinner', // The CSS class to assign to the spinner
      zIndex: 2e9, // The z-index (defaults to 2000000000)
      top: 'auto', // Top position relative to parent in px
      left: 'auto' // Left position relative to parent in px
    };
    $('#loading_anim').each(function() {
        spinner = new Spinner(opts).spin(this);
    });
}
</script>

If you use an animated (GIF) the animation may freeze on some browsers. I used spin.js library ( http://fgnass.github.com/spin.js/ ). While GIFs get frozen the javascript animation seems to be working.

Please test with ALL browsers!

Answer 3

You can do this :

$(function(){
​  $('a').click(function(){
     $('<div class=loadingDiv>loading...</div>').prependTo(document.body); 
  });​
});

Demonstration (change the link to a very slow page for best effect)

But it depends on the page : if the page sends immediately some content but not the whole content, you won't have the time to see your div.