我有这段代码，我总是要在文档的开头创建const ctx，类中使用的名称相同，我想知道是否有办法让这个类对其他项目更容易移植

const canvas = document.getElementById('canvas1');
const ctx = canvas.getContext('2d');

class layer{
    constructor(image, speedModifier){
        this.x = 0;
        this.y = 0;
        this.width = 2400;
        this.height = 700;
        //this.x2 = this.width;
        this.image = image;
        this.speedModifier = speedModifier;
        this.speed = gameSpeed * this.speedModifier
    }
    update(){
        this.speed = gameSpeed * this.speedModifier;
        this.x = gameFrame * this.speed % this.width;
    }
    draw(){
        ctx.drawImage(this.image, this.x, this.y, this.width, this.height);
        ctx.drawImage(this.image, this.x + this.width, this.y, this.width, this.height);
    }
}

顺晟科技：