jQuery: Append browser window dimensions to href

I am wanting to use jQuery to add the current browser window dimensions to the end of the href of certain a tags.

The specific a tags all have their href begin with secondary_imgs.php but other than that, differ by containing data, i.e. secondary_imgs.php?Id=x&Title=y. I could easily set all these tags to have a specific class if that helps the probl开发者_Python百科em.

I think the best approach to this would be to append the &width=x&height=y to the end of the href on document ready, and then set a second function to replace those values, whenever the page is resized.

Alas, I am at a loss as to how to complete this. I have the constituent parts (I think), but need help combining them in the proper way.

Here's what I have thus far:

$(document).ready(function () {
    var width = $(window).width();
    var height = $(window).height();
    $("a[href^='secondary_imgs.php']").attr('href', function() {
        return this.append('&w=width&h=height') 
    });
});

I tried to specify just the a tags who's href begins with secondary_imgs.php. I think that would be the best way of specifying it. But beyond that, I don't know where I'm making a mistake.

For the second half of this, where the values are replaced when the window is resized, I thought using .resize() would be the best to trigger the function, however I don't know how to set it up to replace the values, not add to them.

Any help would be much appreciated. Thank you.

In the loop this refers to a DOM element, so you can't use the append method on it. Besides, the append method adds elements inside an element, it doesn't concatenate strings.

To put the values of the width and height variables in the string you have to concatentate them into a string. Putting the variable names inside a string won't evaluate them.

$(document).ready(function () {
  var width = $(window).width();
  var height = $(window).height();
  $("a[href^='secondary_imgs.php']").attr('href', function(index, attr) {
    return attr + '&w=' + width + '&h=' + height; 
  });
});

If you want to get the window size at the moment that the user clicks on the link instead of the size when the page loads, then you would rather catch the click event, create a new URL and apply it yourself instead:

$(document).ready(function () {
  $("a[href^='secondary_imgs.php']").click(function(e){
    e.preventDefault(); // stop the click
    var width = $(window).width();
    var height = $(window).height();
    var url = $(this).attr('href') + '&w=' + width + '&h=' + height;
    window.location.href = url; // replace the link action
  });
});

Edit:

To be compatible with other scripts that take over the link action, you would make sure that you bind your event before loading/activating that script, and only change the URL and write it back, but first checking if there are properties that needs to be removed:

$(document).ready(function () {
  $("a[href^='secondary_imgs.php']").click(function(e){
    var width = $(window).width();
    var height = $(window).height();
    var url = $(this).attr('href');
    var idx = url.indexOf('&w=');
    if (idx != -1) {
      url = url.substr(0, idx);
    }
    url += '&w=' + width + '&h=' + height;
    $(this).attr('href', url);
  });
});

Can I suggest a different approach?

If you wait until someone clicks on the link, then you only have to do the calculation once and can forget about the resize. Simply bind to the link's click event:

(function($) {
  $(document).ready(function () {
    $("a[href^='secondary_imgs.php']").bind({
      'click'  :  function(e) {
        var w = $(window).width();
        var h = $(window).height();
        $(this).attr('href', function() {
          return this.append('&w='+w+'&h='+h) ;
        });
      }
    }) ;
  });
})(jQuery) ;

N.B. - you will still need to ensure that your href contains a '?' before using '& as the first appended character.

I think the problem is in this line:

this.append('&w=width&h=height')

Try

$(this).attr('href', function(i, val) {
      return val + '&w=width&h=height';
});