How to get image dimensions on Cloudflare Workers?

Question

I'm trying to create a Cloudflare Worker that receives an image URL and return width and height . But I receive the message ReferenceError: Image is not defined for new Image() . Is there a workaround to make the code below work?

addEventListener('fetch', event => {
  event.respondWith(handleRequest(event.request))
})

async function handleRequest(request) {
  let imageUrl = new URL(request.url).searchParams.get('imageUrl')

  let response = await fetch(imageUrl)
  let blob = await response.blob()

  let image = new Image() // <------ ReferenceError: Image is not defined
  return new Promise((resolve, reject) => {
    image.onload = function() {
      resolve(new Response(JSON.stringify({
        width: image.width,
        height: image.height
      }), {
        headers: {
          'content-type': 'application/json'
        }
      }))
    }
    image.onerror = reject
    image.src = URL.createObjectURL(blob)
  })
}

It seems other functions for images have a similar problem. Example: ReferenceError: createImageBitmap is not defined . So any possible solution would be great.

Answer 1

Image are only available in the browse. If you want to get the width and height of an image in node.js try this

const http = require('http');
const fs = require('fs');
const gm = require('gm');

async function handleRequest() {
    const filename = "image.png"
    const fileURL  = "https://any-page.dom/"+filename
    const file = fs.createWriteStream(filename);

    return new Promise((resolve, reject) => {
        const request = http.get(fileURL, function(response) {
            response.pipe(file);
            // after download completed close filestream
            file.on("finish", () => {
                console.log("Download Completed");
                file.close();
                gm(filename)
                 .size(function (err, size) {
                     if (!err) {
                         console.log('width = ' + size.width);
                         console.log('height = ' + size.height);
                         resolve(new Response(JSON.stringify({
                            width: size.width,
                            height: size.height
                          }), {
                            headers: {
                              'content-type': 'application/json'
                            }
                          }))
                     } else {
                        reject(err)
                     }
                 });
            });
         });
      })
  }