append-px-if-needed.js

/* @flow */

// Copied from https://github.com/facebook/react/blob/
// b87aabdfe1b7461e7331abb3601d9e6bb27544bc/
// packages/react-dom/src/shared/CSSProperty.js
const isUnitlessNumber = {
  animationIterationCount: true,
  borderImageOutset: true,
  borderImageSlice: true,
  borderImageWidth: true,
  boxFlex: true,
  boxFlexGroup: true,
  boxOrdinalGroup: true,
  columnCount: true,
  columns: true,
  flex: true,
  flexGrow: true,
  flexPositive: true,
  flexShrink: true,
  flexNegative: true,
  flexOrder: true,
  gridArea: true,
  gridRow: true,
  gridRowEnd: true,
  gridRowSpan: true,
  gridRowStart: true,
  gridColumn: true,
  gridColumnEnd: true,
  gridColumnSpan: true,
  gridColumnStart: true,
  fontWeight: true,
  lineClamp: true,
  lineHeight: true,
  opacity: true,
  order: true,
  orphans: true,
  tabSize: true,
  widows: true,
  zIndex: true,
  zoom: true,

  // SVG-related properties
  fillOpacity: true,
  floodOpacity: true,
  stopOpacity: true,
  strokeDasharray: true,
  strokeDashoffset: true,
  strokeMiterlimit: true,
  strokeOpacity: true,
  strokeWidth: true
};

export default function appendPxIfNeeded(
  propertyName: string,
  value: any
): string {
  const needsPxSuffix =
    !isUnitlessNumber[propertyName] && typeof value === 'number' && value !== 0;
  return needsPxSuffix ? value + 'px' : value;
}