I am trying to make a robot that can perform certain animations when keys are pressed.

When I press the "J" key I would like the robot to jump up and down.

I am using Three.js and Tween.js to accomplish this. So far I have a scene made with light and a camera. I am creating the different parts of the robot through functions. I have an example of one of these functions below.

function createHead() {
      const head = new THREE.Mesh( new THREE.BoxGeometry(30, 30, 30),
        new THREE.MeshLambertMaterial({ color: 0x669999 }));
      head.position.y = 30;
      head.position.z = -250;
      head.rotation.y = 5;
      scene.add(head);

      var jumpTween = new TWEEN.Tween(head.position).to({y: head.position.y+20}, 1000).repeat(1).yoyo(true).start();
    }

Here is my function for updating

function update (event) {
      if (String.fromCharCode(event.keyCode) == "J" || isJumping) 
      {
        isJumping = true;
        TWEEN.update();
      }

      // Draw!
      renderer.render(scene, camera);

      // Schedule the next frame.
      requestAnimationFrame(update);
    }

When I press "J" my robot jumps once and only once. I cannot press "J" again to get the robot to perform another jump. I was hoping there would be away to just simply "call" a tween on command and have it play on command. However, it seems like TWEEN.update() is the only function that actually runs the tween and in this case, it only runs once. I have been reading the documentation for Tween.js but I am not finding anything helpful.

Edit: I have also tried adding this to my tween.

.onComplete(() => {isJumping = false})

so that it would set isJumping back to false when the animation completes but this did not work.

Thanks for the help.