sketch.js

var movingrect,fixedrect; 
function setup() {
  
  createCanvas(800,400);
  movingrect = createSprite(400, 200, 50, 50);
  movingrect.shapeColor = "green";
  movingrect.debug = "true";
  fixedrect = createSprite(400,100,50,100);
  fixedrect.shapeColor = "green";
fixedrect.debug = "true";

}

function draw() {
  background(0);
  movingrect.x = World.mouseX
  movingrect.y = World.mouseY  

  if(movingrect.x-fixedrect.x<= movingrect.width/2+fixedrect.width/2 && 
    fixedrect.x-movingrect.x <=  movingrect.width/2+fixedrect.width/2&&
    movingrect.y-fixedrect.y<= movingrect.height/2+fixedrect.height/2 && 
    fixedrect.y-movingrect.y <=  movingrect.height/2+fixedrect.height/2){

    movingrect.shapeColor = "red";
    fixedrect.shapeColor = "red";
  }
  else{
    movingrect.shapeColor = "green";
    fixedrect.shapeColor = "green"; 
  }
  drawSprites();
}