Failed Collision detection function

Question

I have made a game using p5.js. The player is the white square and the walls are blue. I have made a collison detection function, but it is pretty spotty. Sometimes, it works fine, but other times there is a slight distance between the player and the wall. Can you please tell me what is going wrong? Any help would be greatly appreciated! Code is below:

function collide(a, b, dx, dy){
  var newx = a.x + dx * playerSpeed;
  var newy = a.y + dy * playerSpeed;
  if (newx < b.x + b.size && newx + a.size > b.x && newy < b.y + b.size && newy + a.size > b.y){
    return true;
  }
  return false;
}

For full code go to https://replit.com/@TonyWu4/Project

If you want examples on what is happening, Links to screenshots are below.

Working Fine

Not working