How to Enforce Image Dimension Limitations Using JavaScript?

Enforce Dimension Limitations on Image Uploads Using JavaScript

In the pursuit of controlling user uploads, you may encounter the need to check image width and height before submitting them to a server. This JavaScript functionality provides an elegant solution to filter images that meet specified criteria.

To achieve this, we create an image object from the selected file using the File API. Here's how it works:

 function checkImageDimensions(target) {
   const file = target.files[0];

   // Create an image object to access its properties
   const img = new Image();
   const objectUrl = URL.createObjectURL(file);

   img.onload = function() {
     const width = this.width;
     const height = this.height;

     if (width > 240 || height > 240) {
       alert("Image dimensions exceed maximum (240x240)");
       return false;
     } else {
       // Image meets the dimension criteria
       // Continue with the upload process
       return true;
     }
   };

   img.src = objectUrl;
 }

 // Bind the event listener to the file input
 document.getElementById("photoInput").addEventListener("change", checkImageDimensions);

In this script, we:

1. Create an image object from the uploaded file.
2. Attach a load event listener to the image object.
3. Inside the load event handler, obtain the image dimensions and compare them to the specified maximum.
4. Display an alert if the dimensions are exceeded, indicating whether the image is accepted or not.

This approach ensures that uploaded images adhere to your desired dimensions, providing a more controlled user experience and preventing potential display issues on your website.

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