Calculation of the coordinates or a point in the middle of two points

middle_point_coordinates.js

function distancePoints( xA, yA, xB, yB ){
  var xDistance = Math.abs( xA - xB );
  var yDistance = Math.abs( yA - yB );

  return Math.sqrt( Math.pow( xDistance, 2 ) + Math.pow( yDistance, 2 ) );
}

function coordinatesMediumPoint( xA, yA, xB, yB, distanceAC ){
  var distanceAB  = distancePoints( xA, yA, xB, yB );
  var angleAB     = Math.atan2( ( yB - yA ), ( xB - xA ) );
  var deltaXAC    = distanceAC * Math.cos( angleAB );
  var deltaYAC    = distanceAC * Math.sin( angleAB );
  
  var xC          = xA + deltaXAC;
  var yC          = yA + deltaYAC;

  return { x: xC, y: yC };
}

hello can you tell me what unit of measurement is the distance