Function registerStylesIE

src/index.ts:248–282

* Registers a set of style text, for IE 9 and below, which has a ~30 style element limit so we need * to register slightly differently. * @param {ThemableArray} styleArray Array of IThemingInstruction objects to register. * @param {IStyleRecord} styleRecord May specify a style Element to update.

(styleArray: ThemableArray, styleRecord?: IStyleRecord)

 * @param {IStyleRecord} styleRecord May specify a style Element to update.
 */
function registerStylesIE(styleArray: ThemableArray, styleRecord?: IStyleRecord): void {
  const head: HTMLHeadElement = document.getElementsByTagName('head')[0];
  let { lastStyleElement, registeredStyles }: IThemeState = _themeState;

  const stylesheet: IStyleSheet = lastStyleElement ? lastStyleElement.styleSheet : undefined;
  const lastStyleContent: string = stylesheet ? stylesheet.cssText : '';
  let lastRegisteredStyle: IStyleRecord = registeredStyles[registeredStyles.length - 1];
  const resolvedStyleText: string = resolveThemableArray(styleArray);

  if (!lastStyleElement || (lastStyleContent.length + resolvedStyleText.length) > MAX_STYLE_CONTENT_SIZE) {
    lastStyleElement = document.createElement('style') as IExtendedHtmlStyleElement;
    lastStyleElement.type = 'text/css';

    if (styleRecord) {
      head.replaceChild(lastStyleElement, styleRecord.styleElement);
      styleRecord.styleElement = lastStyleElement;
    } else {
      head.appendChild(lastStyleElement);
    }

    if (!styleRecord) {
      lastRegisteredStyle = {
        styleElement: lastStyleElement,
        themableStyle: styleArray
      };
      registeredStyles.push(lastRegisteredStyle);
    }
  }

  lastStyleElement.styleSheet.cssText += detokenize(resolvedStyleText);
  Array.prototype.push.apply(lastRegisteredStyle.themableStyle, styleArray); // concat in-place

  // Preserve the theme state.
  _themeState.lastStyleElement = lastStyleElement;
}

/**
 * Checks to see if styleSheet exists as a property off of a style element.