3d robotic arm with Three.js + rapier.js physics engine
Live demo here (original here). Use G to open/close grip, Z to toggle zoom by mousewheel.
You can move the grip using the mouse and see the linkage follow it. No need for inverse kinematic implementation.
Definition of the robot arm is in robot.jshttps://github.com/jumpjack/robot-arm-3d-with-physics/blob/master/robot.js.