​

function setup() {

  createCanvas(400, 400);

  button = createButton("randomize!"); // create a button called "randomize!"

  button.mousePressed(changeBG); // executes changeBG() when button is pressed

  background(random(255),random(255),random(255));

}

​

function changeBG(){

  background(random(255),random(255),random(255));

}