How remove IMG classes?

Hello @gorem,

The filter add_filter( 'get_image_tag_class', '__return_empty_string' ); only removes the classes when you add new images. It did not remove classes of existing images.

Please note that the filter you’re using only empties the classes, but will keep the class element. Thus your images will look as follow:

<img src="https://mydomain.com/wp-content/uploads/myimage.png" class="" alt="" width="150" height="150" />

If you want to remove the entire class element, please use the following code snippet:

add_filter('get_image_tag', 'strip_entire_image_class');
function strip_entire_image_class($html) {
  return preg_replace('/ class="(.*)"/', '', $html);
}

Using this snippet let’s your images look like this:

<img src="https://mydomain.com/wp-content/uploads/myimage.png" alt="" width="150" height="150" />

Have I mentioned that I would not recommend to remove the classes in first place? I assume you have a good reason to remove them in your case.

Best,
Niels

• This reply was modified 7 years, 10 months ago by Niels Lange.

Hello Niels,
thanks you.
No, you didn’t mentioned why you wouldn’t recommend it ?? Can you do it please?
Im not using img classes, so I thought it is good idea to strip them out.

Snippet doens’t work:

add_filter('get_image_tag', 'strip_entire_image_class');
function strip_entire_image_class($html) {
  return preg_replace('/ class="(.*)"/', '', $html);
}

• This reply was modified 7 years, 10 months ago by gore.m.

Works for me. It will typically only work for newly inserted images. Once inserted, the classes become part of the content and you’d need to edit the content to remove classes. Also, if any function besides get_image_tag() is used, this code would have no effect.

I agree with Niels, this is not a good idea. Even if you are not using classes now, they do no harm other than a very small increase in data transmitted. If you should change themes in the future, your new theme may make use of these classes and posts with missing classes will not display correctly. It’s a lot harder to restore missing classes than it is to remove them.

Thanks you.
Strange… it doesnt work for me.
I dont have any get_image_tag() in function.php or in templates.
Classes output even if images are newly inserted. ??

According to your suggestion, what about add my own class and filter default classes out?

Just substitute your own class for the empty replacement in the preg_replace() function. get_image_tag() is a core function used when inserting images through the media library on a post edit screen. It doesn’t matter what theme you have or what’s in functions.php or templates. The substitution is done on insertion, not on output. If images are being placed by some other mechanism, this code will not work. In that case the solution would depend on how the images are being placed.

It’s also possible your theme or one of your plugins is also somehow manipulating the same filter so that this code has no effect. You could try hooking late so your function has the final say.

add_filter('get_image_tag', 'strip_entire_image_class', 999 );
// same function declaration

Thanks you.

Still cant get it work :-/
So for to be clear, Ive tried:

– I disabled “Compress JPEG & PNG images” plugin, that was only one plugin for images.
– Ive tried

add_filter( 'get_image_tag_class', '__return_empty_string', 9999 );

or

function strip_entire_image_class($html) {
    return preg_replace('/ class="(.*)"/', '', $html);
}
add_filter('get_image_tag', 'strip_entire_image_class', 999);

than

– I inserted image with Media > Upload > Chose > edit > Click on link above image / or Insert image to post > Publish > Preview

Nothing happened.
Still have classes attachment-medium size-medium or attachment-large size-large wp-post-image or attachment-shop_single size-shop_single wp-post-image.

Im using _s theme, Ive tried Twenty Eleven with same output.

• This reply was modified 7 years, 9 months ago by stephencottontail.
• This reply was modified 7 years, 9 months ago by gore.m.

“attachment-shop_single”

Shop? Are you using WooCommerce? Adding images through Product Image or Product Gallery? That would qualify as “images are being placed by some other mechanism”. The get_image_tag() is used for images added to post content. WC product images are different. Unfortunately, I’m unsure how product images are handled. I suggest you inquire in the WC dedicated support forum where the WC community would have a better idea of how to remove classes from product images.

OK I disabled Woocommerce and used

add_filter('get_image_tag', 'strip_entire_image_class');
function strip_entire_image_class($html) {
  return preg_replace('/ class="(.*)"/', '', $html);
}

Still It is not working attachment-large size-large wp-post-image.

There could still be influence from your theme or other plugins. Are the images you are using inserted into post content by using the media library? For example, images added as the post’s featured image is not considered as being inserted into post content. Only images added into the tinyMCE editor is part of post content.

Here’s a test to try. Determine the attachment ID of an image. Any image in the media library that has a ‘large’ size will work. On a template somewhere (a page or single post template would be good choices), place the following code, then check the HTML output for class attributes:

// replace ATCH_ID below with an actual attachment ID
echo get_image_tag( ATCH_ID, 'test image', 'Test', 'left', 'large' );

This will confirm if the filter code is working or not. If not, your theme or another plugin is also filtering the same function. You can try adding 999 to the add_filter() line like I suggested a few posts back to see if you can supersede any other filtering.

If this test does remove classes, then the issue is your images are being added in a way that bypasses this function. You’ll need to identify how that is being done in order for a solution to be devised.

Thanks you
Warning: call_user_func_array() expects parameter 1 to be a valid callback, function 'strip_entire_image_class' not found or invalid function name in C:\wamp64\www\wordpress\wp-includes\class-wp-hook.php on line 300
ID is 1104, so I tried 1104 and ‘1104’ … is it right?

Should be an integer, though PHP usually automatically type casts numeric strings to integers, so either should work.
echo get_image_tag( 1104, 'test image', // etc....

Where did you declare the ‘strip_entire_image_class’ function? It’s apparently not available to templates, which may explain why it’s not working for you. The proper places to put a function declaration would be either a child theme’s (or main theme’s if you must) functions.php or the primary page of a plugin (or an always included file of either one).

I used what you recommended before:

You can try adding 999 to the add_filter() line like I suggested a few posts back to see if you can supersede any other filtering.

So I used (in function.php)

add_filter('get_image_tag', 'strip_entire_image_class', 999 );
// same function declaration

I removed it and used echo get_image_tag( 1104, 'test image', 'Test', 'left', 'large' ); than I got classes:

alignleft size-large wp-image-1104

than I tried main:

function strip_entire_image_class($html) {
    return preg_replace('/ class="(.*)"/', '', $html);
}
add_filter('get_image_tag', 'strip_entire_image_class', 999);

And it is working!.. no classes ??

So is it plugin or theme, how would you search for origin?

thanks you

How to search for origin of conflict? Disable all plugins. If the classes are gone, it was a plugin. If still a problem, it is the theme. You could then activate each plugin one at a time until the classes reappear. The last activated plugin is the cause. To remove a filter added by theme or plugin, you need to know the add_filter() parameters used. You could grep for “get_image_tag” or var_dump the global $wp_filter and deduce the parameters from where the callback is located in the array structure.

That said, I don’t think the problem was a conflicting filter. Since moving the declaration solved the problem without removing any other filter, I have to think the original location was the wrong place to begin with. You said you moved it from function.php. If accurate, that is the wrong file. The proper location in a theme folder is functions.php (plural with an ‘s’) I suspect that was a typo and you meant functions.php. In that case, the only explanation is you chose the functions.php of the wrong theme, or the code was placed in the wrong place within that file, such as within a class or function declaration.

Whatever it was, it doesn’t matter much now. You got it working! Awesome! ??

Thanks you.
Yes, it was typo, everytime Im using functions.php.

I did test… so it is not an plugin, I disabled all and featured image still has same classes, without any change, so it has to be theme.
Im using _s Underscore, I haven’t been doing any changes regarding to images…
I was looking at functions.php there is only support add_theme_support( 'post-thumbnails' ); and in content.php template is <?php the_post_thumbnail('large');?>.. thats all I found… So, instead of looking for disabling should I use an function to adjust output?

Adjusting output, so even though it is in post content, strip out classes on output? That’s possible. The filter “the_content” could be used. In fact, almost the same callback can be used. The regexp needs to be adjusted so it only strips classes of img tags and not all classes. Untested, but something like this (added to functions.php):

function strip_entire_img_class($html) {
    return preg_replace('/<img .*class="(.*)"/', '', $html);
}
add_filter('the_content', 'strip_entire_img_class');

“the_content” would be an unfortunate solution because it is much less efficient.

The classes that will not go away are within double quotes, right?
class="alignleft size-large wp-image-1104"
Single quotes are valid HTML, but will not get picked up by the regexp we’ve been using. A long shot. I’m 99% certain they’re double, but a 1% chance is worth confirming at this point.

The previous code is not working? But it works on main? What do you mean by “main”? It feels like we’re missing something simple if it’s working there but not otherwise. From what I know of Underscore (very little), it’s unlikely to cause conflicts. The previous code works on my site, which is virtually the default WP installation, so it ought to work on yours with Underscore and no plugins IF we are going about images in the same way. There’s a disconnect somewhere, but I can’t imagine what it might be. Maybe if I understood “main” better, I’ll get an idea.