Method _initializeSubscript

src/material/form-field/form-field.ts:523–539

* Initializes the subscript by validating hints and synchronizing "aria-describedby" ids * with the custom form field control. Also subscribes to hint and error changes in order * to be able to validate and synchronize ids on change.

()

   * to be able to validate and synchronize ids on change.
   */
  private _initializeSubscript() {
    // Re-validate when the number of hints changes.
    this._hintChildren.changes.subscribe(() => {
      this._processHints();
      this._changeDetectorRef.markForCheck();
    });

    // Update the aria-described by when the number of errors changes.
    this._errorChildren.changes.subscribe(() => {
      this._syncDescribedByIds();
      this._changeDetectorRef.markForCheck();
    });

    // Initial mat-hint validation and subscript describedByIds sync.
    this._validateHints();
    this._syncDescribedByIds();
  }

  /** Throws an error if the form field's control is missing. */
  private _assertFormFieldControl() {