html 


	<img class="dynamicImage" src="" alt="Dynamic 59 Image">
      
 javascript 

<script>
document.addEventListener("DOMContentLoaded", function () {
    var pageWidth = window.innerWidth || document.documentElement.clientWidth || document.body.clientWidth;
    console.log(pageWidth);

    // Check the page width and set the image source accordingly
    var imgSource = (pageWidth > 991) ? "<?php echo $img_url; ?>" : "<?php echo $img_url_mobile; ?>";
console.log(imgSource);
	console.log("test image url");
    // Set the image source dynamically
    console.log(document.getElementsByClassName("dynamicImage")[0]);
	var img_tag_nmb = document.getElementsByClassName("dynamicImage");
	for (let i = 0; i < img_tag_nmb.length; i++) {
  console.log(i);
		document.getElementsByClassName("dynamicImage")[i].src = imgSource;
}
});
</script>









<-- 	without console.log		--> 

<script>
document.addEventListener("DOMContentLoaded", function () {
    var pageWidth = window.innerWidth || document.documentElement.clientWidth || document.body.clientWidth;

    var imgSource = (pageWidth > 991) ? "<?php echo $img_url; ?>" : "<?php echo $img_url_mobile; ?>";

	var img_tag_nmb = document.getElementsByClassName("dynamicImage");
	for (let i = 0; i < img_tag_nmb.length; i++) {

		document.getElementsByClassName("dynamicImage")[i].src = imgSource;
}

});
</script>