Trying to use polymorph with nim js backend. It does not work. File created to submit an issue.

The following code is executed by nimib both using c backend and js backend.

If you open the browser console you will see that with js backend:

• it starts with Pos (0, 0) instead of (1, 1) (and wrong velociy)
• at each step neither move nor gravity are applied, only bounce is applied.

import polymorph

# Parse some types as components.
register defaultCompOpts:
  type
    Pos = object
      x, y: float
    Vel = object
      x, y: float
    Gravity = object
      strength: float
    Bounce = object   # A dataless 'tag' component.

makeSystem "move", [Pos, Vel]:
  # Calculate basic movement.
  all:
    echo "move"
    pos.x += vel.x
    pos.y += vel.y

makeSystem "gravity", [Vel, Gravity]:
  # Apply a gravity force to 'Vel'.
  all:
    vel.y -= gravity.strength

makeSystem "bounce", [Pos, Vel, Bounce]:
  all:
    # Correct 'Pos.y' to never goes below zero, enacting a simple bounce
    # to 'Vel.y' if this occurs.
    if pos.y <= 0.0:
      pos.y = 0.0
      vel.y = abs(vel.y) * 0.5

# Generate the framework and system procedures.
makeEcsCommit "run"

let
  ball = newEntityWith(
    Pos(x: 0.0, y: 0.0),
    Vel(x: 1.0, y: 1.0),
    Gravity(strength: 1.0),
    Bounce()
  ) 

for i in 0 ..< 4:
  run()
  echo ball

move
[EntityId: 1 (generation: 1)
Alive: true
Components:
  Pos (id: 1, index: 1, generation: 1): (x: 1.0, y: 1.0)
  Vel (id: 2, index: 1, generation: 1): (x: 1.0, y: 0.0)
  Gravity (id: 3, index: 1, generation: 1): (strength: 1.0)
  Bounce (id: 4, index: 1, generation: 1): ()
Systems:
  move (sysMove) 
  gravity (sysGravity) 
  bounce (sysBounce) 
]
move
[EntityId: 1 (generation: 1)
Alive: true
Components:
  Pos (id: 1, index: 1, generation: 1): (x: 2.0, y: 1.0)
  Vel (id: 2, index: 1, generation: 1): (x: 1.0, y: -1.0)
  Gravity (id: 3, index: 1, generation: 1): (strength: 1.0)
  Bounce (id: 4, index: 1, generation: 1): ()
Systems:
  move (sysMove) 
  gravity (sysGravity) 
  bounce (sysBounce) 
]
move
[EntityId: 1 (generation: 1)
Alive: true
Components:
  Pos (id: 1, index: 1, generation: 1): (x: 3.0, y: 0.0)
  Vel (id: 2, index: 1, generation: 1): (x: 1.0, y: 1.0)
  Gravity (id: 3, index: 1, generation: 1): (strength: 1.0)
  Bounce (id: 4, index: 1, generation: 1): ()
Systems:
  move (sysMove) 
  gravity (sysGravity) 
  bounce (sysBounce) 
]
move
[EntityId: 1 (generation: 1)
Alive: true
Components:
  Pos (id: 1, index: 1, generation: 1): (x: 4.0, y: 1.0)
  Vel (id: 2, index: 1, generation: 1): (x: 1.0, y: 0.0)
  Gravity (id: 3, index: 1, generation: 1): (strength: 1.0)
  Bounce (id: 4, index: 1, generation: 1): ()
Systems:
  move (sysMove) 
  gravity (sysGravity) 
  bounce (sysBounce) 
]