Benny Sutton is 4 hire - just click here

Magnifying Glass With CSS JavaScript

A nifty magnifier you can move over an image with your mouse

Demo: How to create a magnifying glass with CSS JavaScript

JavaScript

This is quite complicated JavaScript. I wouldn't edit unless you know what you are doing! You'll paste into your page script block - or in a .js file if you prefer.

         
        function magnify(imgID, zoom) {
          var img, glass, w, h, bw;
          img = document.getElementById(imgID);
          /*create magnifier glass:*/
          glass = document.createElement("DIV");
          glass.setAttribute("class", "img-magnifier-glass");
          /*insert magnifier glass:*/
          img.parentElement.insertBefore(glass, img);
          /*set background properties for the magnifier glass:*/
          glass.style.backgroundImage = "url('" + img.src + "')";
          glass.style.backgroundRepeat = "no-repeat";
          glass.style.backgroundSize = (img.width * zoom) + "px " + (img.height * zoom) + "px";
          bw = 3;
          w = glass.offsetWidth / 2;
          h = glass.offsetHeight / 2;
          /*execute a function when someone moves the magnifier glass over the image:*/
          glass.addEventListener("mousemove", moveMagnifier);
          img.addEventListener("mousemove", moveMagnifier);
          /*and also for touch screens:*/
          glass.addEventListener("touchmove", moveMagnifier);
          img.addEventListener("touchmove", moveMagnifier);
          function moveMagnifier(e) {
            var pos, x, y;
            /*prevent any other actions that may occur when moving over the image*/
            e.preventDefault();
            /*get the cursor's x and y positions:*/
            pos = getCursorPos(e);
            x = pos.x;
            y = pos.y;
            /*prevent the magnifier glass from being positioned outside the image:*/
            if (x > img.width - (w / zoom)) {x = img.width - (w / zoom);}
            if (x < w / zoom) {x = w / zoom;}
            if (y > img.height - (h / zoom)) {y = img.height - (h / zoom);}
            if (y < h / zoom) {y = h / zoom;}
            /*set the position of the magnifier glass:*/
            glass.style.left = (x - w) + "px";
            glass.style.top = (y - h) + "px";
            /*display what the magnifier glass "sees":*/
            glass.style.backgroundPosition = "-" + ((x * zoom) - w + bw) + "px -" + ((y * zoom) - h + bw) + "px";
          }
          function getCursorPos(e) {
            var a, x = 0, y = 0;
            e = e || window.event;
            /*get the x and y positions of the image:*/
            a = img.getBoundingClientRect();
            /*calculate the cursor's x and y coordinates, relative to the image:*/
            x = e.pageX - a.left;
            y = e.pageY - a.top;
            /*consider any page scrolling:*/
            x = x - window.pageXOffset;
            y = y - window.pageYOffset;
            return {x : x, y : y};
          }
        }

        magnify("myimage", 3);
        
    

CSS

Edit as necessary.

        
            * {box-sizing: border-box;}

            .img-magnifier-container {
              position:relative;
            }

            .img-magnifier-glass {
              position: absolute;
              border: 3px solid #000;
              border-radius: 50%;
              cursor: none;
              /*Set the size of the magnifier glass:*/
              width: 100px;
              height: 100px;
            }
        
    

Conclusion

A few lines of JQuery and CSS is all you need to magnifying glass with css javascript