modules/layers/src/solid-polygon-layer/polygon.js
function isFlatRingClosed(positions, size, startIndex, endIndex) {
  for (let i = 0; i < size; i++) {
    if (positions[startIndex + i] !== positions[endIndex - size + i]) {
      return false;
    }
  }
  return true;
}
function isFlatRingClosed(positions, size, startIndex, endIndex) {
  for (let i = 0; i < size; i++) {
    if (positions[startIndex + i] !== positions[endIndex - size + i]) {
      return false;
    }
  }
  return true;
}
function isFlatRingClosed ( positions , size , startIndex , endIndex ) { for ( let i = 0 ; i < size ; i ++ ) { if ( positions [ startIndex + i ] !== positions [ endIndex - size + i ] ) { return false ; } } return true ; }
Check if a simple flat array is a closed ring
@param {Array} positions - array of numbers
@param {Number} size - size of a position, 2 (xy) or 3 (xyz)
@param {Number} startIndex - start index of the path in the positions array
@param {Number} endIndex - end index of the path in the positions array
@return {Boolean} - true if the simple flat array is a closed ring
Check if a simple flat array is a closed ring