constructor({ x, y, image })
...
this.image = image
this.width = image.width
this.height = image.height
...

This is the addition I made to when I construct an object. I have an image argument so I can add an image to the object. The second block changes the size of the platform, background, and such to conform to the size of the image.

const image = new Image()
This is a constant that allows me to create many images, and different images, just by using this one variable.

class GenericObject {
constructor({ x, y, image }) {
this.position = {
x,
y
}
this.image = image
this.width = image.width
this.height = image.height
}
...
}
...
genericObjects = [
new GenericObject({
x: 0,
y: 0,
image: backgroundImage
}),
]

This is the generic objects class. This hold the background image and the building image for the backdrop. This code has a class that constructs and there is also a genericObjects array that hold all of the GenericObject objects.