im trying to make a canvas object with multiple layers. My code

loadImage('./assets/bg/4.png', './assets/tree/1.png').then((image) => {
ctx.drawImage(image,0,0,256,256)
image = './assets/tree/1.png'
ctx.drawImage(image,0,0,256,256)
    console.log('<img src="' + canvas.toDataURL() + '"/>')
})

How can I do this?