Comments on: Preloading images from a directory

By: Matt

Matt — Wed, 13 May 2009 00:04:50 +0000

Excellent script James, thanks for your work on it. I am fairly green with PHP and JavaScript, is there a way to pre-load not only all the images in a given directory but also in any sub-directories of the given directory?

Thank you

By: JD

JD — Fri, 06 Mar 2009 23:15:59 +0000

looks like it blanked my codeblock….

was coded text

By: JD

JD — Fri, 06 Mar 2009 23:15:02 +0000

What was the code block that you use in the foreach loop?
I tried using this “moments ago” and for some reason the
php code block destroys all coding below it? Weird…

insert method was just
[code] [/code]
JS on page. Any ideas?

By: Ibrahim

Ibrahim — Wed, 07 Jan 2009 13:50:49 +0000

Thanks James 🙂

By: James

James — Wed, 07 Jan 2009 11:38:13 +0000

Hi Ibrahim, yep sure, I’ll explain:

It is a ternary operator which is really a shortcut to using if{}else{}. This is the format of a ternary operator:

(CONDITION) ? TRUE : FALSE;
 
// An example:
echo (2+2) == 4 ? 'YES' : 'NO'; // This will echo "YES"

By: Ibrahim

Ibrahim — Wed, 07 Jan 2009 09:47:58 +0000

Hi James
Plz could you explain to me how this line works

 $arrayContents .= !empty($arrayContents) ? ',' : '';
 // i mean ? : ;

By: James

James — Wed, 07 Jan 2009 08:21:08 +0000

Thanks Vasili, I’ve changed it to a foreach loop; should be a little more efficient. 🙂

@Antione, I could have just used PHP to output the JSON within the page on the server-side instead of requesting it but I thought this might make it a little more interesting + you’re not limited to one request this way – so if the contents of the directory changes while a user is browsing they will still have the latest. (You’d have to change the JS to use some type of setInterval though). To be honest this was more of a proof of concept than anything else. Also, I didn’t use json_encode because all I wanted was an array with the first property of an object, I’d heard that json_encode tends to make normal arrays into associative arrays (~objects) which I didn’t want…

If you’re using a library I know a few of them have their own JSON request methods, so you can just swap out ‘getJSON’ for that…

By: Antoine Leclair

Antoine Leclair — Wed, 07 Jan 2009 04:45:02 +0000

Nice. We don’t see too much of those “pure JavaScript” blog posts since libraries became so popular.

I’m not sure to understand the reason why you went through so much trouble though.

Couldn’t you have simply passed a JSON object from PHP (with json_encode()) containing the filenames and use your preload function to load the images?

I am not a JavaScript expert, I may simply be missing the point here.

By: Vasili

Vasili — Wed, 07 Jan 2009 00:51:30 +0000

You shouldn’t use count($dirContents) in the for loop because it gets called every time the loop is run. 😉