JavaScript を使用して画像の寸法制限を強制する方法

 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);