Function bindingUpdated

packages/core/src/render3/bindings.ts:44–85

(lView: LView, bindingIndex: number, value: any)

 *          `CheckNoChangesMode`)
 */
export function bindingUpdated(lView: LView, bindingIndex: number, value: any): boolean {
  ngDevMode &&
    assertLessThan(bindingIndex, lView.length, `Slot should have been initialized to NO_CHANGE`);

  if (value === NO_CHANGE) {
    return false;
  }

  const oldValue = lView[bindingIndex];

  if (Object.is(oldValue, value)) {
    return false;
  } else {
    if (ngDevMode && isInCheckNoChangesMode()) {
      // View engine didn't report undefined values as changed on the first checkNoChanges pass
      // (before the change detection was run).
      const oldValueToCompare = oldValue !== NO_CHANGE ? oldValue : undefined;
      if (!devModeEqual(oldValueToCompare, value)) {
        const details = getExpressionChangedErrorDetails(
          lView,
          bindingIndex,
          oldValueToCompare,
          value,
        );
        throwErrorIfNoChangesMode(
          oldValue === NO_CHANGE,
          details.oldValue,
          details.newValue,
          details.propName,
          lView,
        );
      }
      // There was a change, but the `devModeEqual` decided that the change is exempt from an error.
      // For this reason we exit as if no change. The early exit is needed to prevent the changed
      // value to be written into `LView` (If we would write the new value that we would not see it
      // as change on next CD.)
      return false;
    }
    lView[bindingIndex] = value;
    return true;
  }
}

/** Updates 2 bindings if changed, then returns whether either was updated. */
export function bindingUpdated2(lView: LView, bindingIndex: number, exp1: any, exp2: any): boolean {