let y = 0;

let xjump = 7.3;

let yjump = 5;

​

function setup() {

  createCanvas(400, 400);

  background(255);

  fill(30,20);

  noStroke();

}

​

function draw() {

  colorMode(HSB);

  fill(

    map(x,0,width,0,360),

    map(y,0,height,0,100),

    map(mouseX,0,width,0,100),

    map(mouseY,0,height,0,1)

    );

  rect(x,y,50,50);

  x = x + xjump;

  if(x >= width || x <= 0) {

    xjump = xjump * -1;

  }

​

  y = y + yjump;

  if(y >= height || y <= 0) {

    yjump = yjump * -1;

  }

​

}