Method ngDoCheck

packages/common/src/directives/ng_for_of.ts:253–284

* Applies the changes when needed. * @docs-private

()

   * @docs-private
   */
  ngDoCheck(): void {
    if (this._ngForOfDirty) {
      this._ngForOfDirty = false;
      // React on ngForOf changes only once all inputs have been initialized
      const value = this._ngForOf;
      if (!this._differ && value) {
        if (typeof ngDevMode === 'undefined' || ngDevMode) {
          try {
            // CAUTION: this logic is duplicated for production mode below, as the try-catch
            // is only present in development builds.
            this._differ = this._differs.find(value).create(this.ngForTrackBy);
          } catch {
            let errorMessage =
              `Cannot find a differ supporting object '${value}' of type '` +
              `${getTypeName(value)}'. NgFor only supports binding to Iterables, such as Arrays.`;
            if (typeof value === 'object') {
              errorMessage += ' Did you mean to use the keyvalue pipe?';
            }
            throw new RuntimeError(RuntimeErrorCode.NG_FOR_MISSING_DIFFER, errorMessage);
          }
        } else {
          // CAUTION: this logic is duplicated for development mode above, as the try-catch
          // is only present in development builds.
          this._differ = this._differs.find(value).create(this.ngForTrackBy);
        }
      }
    }
    if (this._differ) {
      const changes = this._differ.diff(this._ngForOf);
      if (changes) this._applyChanges(changes);
    }
  }

  private _applyChanges(changes: IterableChanges<T>) {
    const viewContainer = this._viewContainer;