snake.js

function Snake() {
    this.x = 0;
    this.y = 0;
    this.xSpeed = scale * 1;
    this.ySpeed = 0;
    this.total = 0;
    this.tail = [];
  
    this.draw = function() {
      ctx.fillStyle = "#FFFFFF";
      
      for(let i = 0; i < this.tail.length; i++){
        ctx.fillRect(this.tail[i].x, this.tail[i].y, scale, scale);
      }
      ctx.fillRect(this.x, this.y, scale, scale);
    }
  
    this.update = function() {

      for(let i = 0; i < this.tail.length - 1; i++){
        this.tail[i] = this.tail[i+1];
      }

      this.tail[this.total -1] = { x: this.x, y: this.y };

      this.x += this.xSpeed;
      this.y += this.ySpeed;

      if(this.x > canvas.width){
        this.x = 0;
      }
      if(this.y > canvas.height){
        this.y = 0;
      }
      if(this.x < 0){
        this.x = canvas.width;
      }
      if(this.y < 0){
        this.y = canvas.height;
      }
    }
  
    this.changeDirection = function(direction) {
      switch(direction) {
        case 'Up':
          this.xSpeed = 0;
          this.ySpeed = -scale * 1;
          break;
        case 'Down':
          this.xSpeed = 0;
          this.ySpeed = scale * 1;
          break;
        case 'Left':
          this.xSpeed = -scale * 1;
          this.ySpeed = 0;
          break;
        case 'Right':
          this.xSpeed = scale * 1;
          this.ySpeed = 0;
          break;
      }
    }

    this.eat = function(fruit){
      if(this.x === fruit.x && this.y === fruit.y){
        this.total++;
        return true;
      }
      return false;
    }
}