https://playteq.com/js/image-size.js

1export function getNaturalSize(imgElement) {
2    return new Promise((resolve, reject) => {
3        if (!imgElement) reject("imgElement is null");
4
5        // si déjà chargé
6        if (imgElement.complete && imgElement.naturalWidth > 0) {
7            resolve({
8                width: imgElement.naturalWidth,
9                height: imgElement.naturalHeight
10            });
11            return;
12        }
13
14        // sinon attendre le load
15        imgElement.addEventListener("load", () => {
16            resolve({
17                width: imgElement.naturalWidth,
18                height: imgElement.naturalHeight
19            });
20        }, { once: true });
21
22        imgElement.addEventListener("error", () => {
23            reject("Image failed to load");
24        }, { once: true });
25    });
26}