cargar.js

const imagen = new Image();
imagen.src = "http://localhost/pusheen.png";
imagen.crossOrigin = "anonymous";
imagen.onload = () => {
    let medidaMayor = imagen.width;
    if (imagen.height > medidaMayor) {
        medidaMayor = imagen.height;
    }
    $canvas.width = medidaMayor;
    $canvas.height = medidaMayor;
    context.drawImage(imagen, 0, 0);
};