Function computeStaticStyling

packages/core/src/render3/styling/static_styling.ts:26–52

(
  tNode: TNode,
  attrs: TAttributes | null,
  writeToHost: boolean,
)

 *   - `true` Write to `TNode.styles` / `TNode.classes`
 */
export function computeStaticStyling(
  tNode: TNode,
  attrs: TAttributes | null,
  writeToHost: boolean,
): void {
  ngDevMode &&
    assertFirstCreatePass(getTView(), 'Expecting to be called in first template pass only');
  let styles: string | null = writeToHost ? tNode.styles : null;
  let classes: string | null = writeToHost ? tNode.classes : null;
  let mode: AttributeMarker | 0 = 0;
  if (attrs !== null) {
    for (let i = 0; i < attrs.length; i++) {
      const value = attrs[i];
      if (typeof value === 'number') {
        mode = value;
      } else if (mode == AttributeMarker.Classes) {
        classes = concatStringsWithSpace(classes, value as string);
      } else if (mode == AttributeMarker.Styles) {
        const style = value as string;
        const styleValue = attrs[++i] as string;
        styles = concatStringsWithSpace(styles, style + ': ' + styleValue + ';');
      }
    }
  }
  writeToHost ? (tNode.styles = styles) : (tNode.stylesWithoutHost = styles);
  writeToHost ? (tNode.classes = classes) : (tNode.classesWithoutHost = classes);
}