Image Magnification Effect

HTML

<!-- Lets make a simple image magnifier -->
<div class="magnify">
    <!-- This is the magnifying glass which will contain the original/large version -->
    <div class="large"></div>
    <!-- This is the small image -->
    <img class="small" src="https://kenh14cdn.com/2018/4/13/photo-4-1523613034062930366784.jpg" width="200" />
</div>
<!-- Lets load up prefixfree to handle CSS3 vendor prefixes -->
<script src="http://thecodeplayer.com/uploads/js/prefixfree.js" type="text/javascript"></script>
<!-- You can download it from http://leaverou.github.com/prefixfree/ -->

CSS

/*Some CSS*/
 * {
    margin: 0;
    padding: 0;
}
.magnify {
    width: 200px;
    margin: 50px auto;
    position: relative;
}
/*Lets create the magnifying glass*/
 .large {
    width: 175px;
    height: 175px;
    position: absolute;
    border-radius: 100%;
    /*Multiple box shadows to achieve the glass effect*/
    box-shadow: 0 0 0 7px rgba(255, 255, 255, 0.85), 0 0 7px 7px rgba(0, 0, 0, 0.25), inset 0 0 40px 2px rgba(0, 0, 0, 0.25);
    /*Lets load up the large image first*/
    background: url('http://courses.mansion.fm/photo-5345/files/2014/04/iphone.jpg') no-repeat;
    /*hide the glass by default*/
    display: none;
}
/*To solve overlap bug at the edges during magnification*/
 .small {
    display: block;
}

JavaScript

$(document).ready(function () {

    var native_width = 0;
    var native_height = 0;

    //Now the mousemove function
    $(".magnify").mousemove(function (e) {
        //When the user hovers on the image, the script will first calculate
        //the native dimensions if they don't exist. Only after the native dimensions
        //are available, the script will show the zoomed version.
        if (!native_width && !native_height) {
            //This will create a new image object with the same image as that in .small
            //We cannot directly get the dimensions from .small because of the 
            //width specified to 200px in the html. To get the actual dimensions we have
            //created this image object.
            var image_object = new Image();
            image_object.src = $(".small").attr("src");

            //This code is wrapped in the .load function which is important.
            //width and height of the object would return 0 if accessed before 
            //the image gets loaded.
            native_width = image_object.width;
            native_height = image_object.height;
        } else {
            //x/y coordinates of the mouse
            //This is the position of .magnify with respect to the document.
            var magnify_offset = $(this).offset();
            //We will deduct the positions of .magnify from the mouse positions with
            //respect to the document to get the mouse positions with respect to the 
            //container(.magnify)
            var mx = e.pageX - magnify_offset.left;
            var my = e.pageY - magnify_offset.top;

            //Finally the code to fade out the glass if the mouse is outside the container
            if (mx < $(this).width() && my < $(this).height() && mx > 0 && my > 0) {
                $(".large").fadeIn(100);
            } else {
                $(".large").fadeOut(100);
            }

            if ($(".large").is(":visible")) {
                //The...