getImageWidthByUserContext.js

export const getImageWidthByUserContext = (width, MAX_WIDTH = 2880) => {
  if (typeof(window) === 'undefined') return width;

  // Pixel ratio
  let qualityRatio = window.devicePixelRatio ? window.devicePixelRatio : 1;

  // If bad connection, we downgrade
  let type = null;
  if (navigator && navigator.connection && navigator.connection.type) type = navigator.connection.type;
  if (navigator && navigator.connection && navigator.connection.effectiveType) type = navigator.connection.effectiveType;

  if (type !== null && (type !== 'wifi' && type !== '4g')) qualityRatio = 1;

  width *= qualityRatio;

  if (width > MAX_WIDTH) width = MAX_WIDTH;

  return width;
}