Correct way to rotate objects around a pivot point in threejs

Questions
1

If I have to rotate objects around a pivot point, i follow the following steps:

  • make a list of objects to rotate
  • create a pivot point
  • Attach pivot to object
  • rotate pivot by 90 degrees
  • ?? Do I need to updateMatrixWorld here? or mutiply the pivot world matrix to object position? (To update the position of the object?)
  • add the objects back to the scene
  • delete pivot point
var listofObject = [object1, object2];

var pivot = new THREE.Object3D();
pivot.position.set(0,0,0);
pivot.rotation.set(0,0,0);

for(var i = 0; i < listOfObject.length; i++)
{
   pivot.attach(listofObject[i];
}

//rotate the pivot
pivot.rotation.x = Math.PI / 2;

// I believe i need to update the position of the objects? here how do i do it? 

//then add the object back to the scene

If we were to multiply the position of the object with the pivot world matrix ( which is, i believe, a transformational matrix with only rotation values ) wouldn’t that mess up the position values of the object? ( wounldn’t it return some weird position values? )

Also are any kind of values having “e” in them are normal? cause i get some of those values

Can you point me towards some resources where i can learn more about this?

EDIT: I think i have understood, how everything works and i have successfully solved the issue. The problem was i was using the applyMatrix4() for the wrong object parameter