Create script using instance mode.

this-is-a-test-im-1.js

//instance mode

//template for creating a p5 sketch (kind of)
var sketch = function(p){
  //RGB rainbow colors
  p.rainbowR = [248, 255, 255, 254, 208, 105, 18, 68, 59];
  p.rainbowG = [12, 51, 102, 174, 195, 208, 189, 68, 12];
  p.rainbowB = [18, 17, 68, 45, 16, 37, 185, 221, 189];

  var i;
  var t = p.rainbowR.length;

  p.setup = function(){
    p.createCanvas(640, 100);
    i = 0;
  }

  p.draw = function(){
    //background
    p.background(255);

    //borders
    p.fill(255);
    p.stroke(0);
    p.rect(0, 0, 639, 99);

    //ellipse click
    p.stroke(255);
    p.fill(p.rainbowR[i], p.rainbowG[i], p.rainbowB[i]);
    p.ellipse(p.mouseX, p.mouseY, 50, 50);

    //ellipse static
    p.stroke(255);
    p.fill(0, 100);
    p.ellipse(320, 50, 50, 50);
  }

  p.mousePressed = function(){
    if(i < t - 1){
      i += 1;
    }
    else{
      i = 0;
    }
  }
}

//after we have created the template
//we can create new p5 objects
var myp5_1 = new p5(sketch, 'script-holder-1');