rectangle_intersection.js

// x,y is bottom left corner
var Rectangle = function Rectangle(x,y,w,h){
  this.x = x;
  this.y = y;
  this.width = w;
  this.height = h;
}

// SOLUTION
var checkIntersect = function checkIntersect(r1,r2) {
  if(!intersect(r1,r2)){
    return new Rectangle(0,0,0,0);
  }
  return new Rectangle(
    Math.max(r1.x, r2.x), Math.max(r1.y, r2.y),
    Math.min(r1.x + r1.width, r2.x + r2.width) - Math.max(r1.x, r2.x),
    Math.min(r1.y + r1.height, r2.y + r2.height) - Math.max(r1.y, r2.y)
  )
}

var intersect = function intersect(r1, r2) {
  return r1.x <= (r2.x + r2.width) && (r1.x + r1.width) >= r2.x &&
         r1.y <= (r2.y + r2.height) && (r1.y + r1.height) >= r2.y;
}