Measuring width & height of images returns 0 in Chrome and Firefox, but works in Safari

Question

I'm trying to give my images a landscape or portrait class in a Wordpress image gallery by measuring the images' dimensions on load. The code works in Safari, but Firefox returns a 0 pixel width and height, and Chrome sometimes loads them properly, and sometimes not. I'm pretty confused, could someone help me out?

jQuery(window).on('load', function () {

    jQuery(".blocks-gallery-grid img").each(function() {

        var aspectRatio = jQuery(this).css('width', 'auto').width()/jQuery(this).css('height', 'auto').height();
            console.log(jQuery(this).attr('src'));
            console.log(jQuery(this).width());
            console.log(jQuery(this).height());
        jQuery(this).data("aspect-ratio", aspectRatio);

        if(aspectRatio > 1) {
            jQuery(this).parent().parent().parent('li').addClass( "landscape" );

        } else if (aspectRatio < 1) {
            jQuery(this).parent().parent().parent('li').addClass( "portrait" );
        } else {
            jQuery(this).parent().parent().parent('li').addClass( "landscape" );           
        }
    });
});

Answer 1

$(window).on('load', function() { 
    $(".blocks-gallery-grid img").each(function() {
        let _this = $(this),
            aspectRatio = _this.width()/_this.height(),
            parentLi = _this.closest('li');
            
        if(aspectRatio > 1) {
            parentLi.addClass( "landscape" );
        } else if (aspectRatio < 1) {
            parentLi.addClass( "portrait" );
        } else {
            parentLi.addClass( "landscape" );           
        }
    });
});

img{
  max-width: 100%;
}
li{
   padding: 15px; 
   box-sizing: border-box; 
   border: 3px solid;
}
.landscape{
   border-color: red;
}
.portrait{
   border-color: green;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<ul class="blocks-gallery-grid">
  <li>
    <img src="https://dummyimage.com/600x400/000/fff">
  </li>
  <li>
    <img src="https://dummyimage.com/400x600/000/fff">
   </li>
</ul>

Could you try something like this:

$(window).on('load', function () {

    $(".blocks-gallery-grid img").each(function() {
        let _this = $(this);

        let aspectRatio = _this.width()/_this.height();

        _this.data("aspect-ratio", aspectRatio);

        if(aspectRatio > 1) {
            _this.parent().parent().parent('li').addClass( "landscape" );

        } else if (aspectRatio < 1) {
            _this.parent().parent().parent('li').addClass( "portrait" );
        } else {
            _this.parent().parent().parent('li').addClass( "landscape" );           
        }
    });
});

Also, I assume li is the only list item parent for that element, so you could probably omit all the .parent() selectors and use: .closest().