Error after closing dialog in IE if there was no active element when opening the dialog #2760
Description
Bug, feature request, or proposal:
Bug.
What is the expected behavior?
Dialog closes without throwing a TypeError in IE (for dialog that was opened when there was no element with focus).
What is the current behavior?
I open a dialog by clicking an item in a drop down menu. This drop down menu is then closed immediately, which means that there is no element with focus. In dialog-container the element with focus is stored with:
this._elementFocusedBeforeDialogWasOpened = document.activeElement;
The document.activeElement documentation states that:
When there is no selection, the active element is the page's <body> or null.
I guess that both Chrome and Firefox set the <body> as active element, and IE sets it to null. Because only in IE I get the TypeError:
TypeError: Unable to get property 'focus' of undefined or null reference
When the dialog is trying to re-focus the element with last focus after closing the dialog:
(this._elementFocusedBeforeDialogWasOpened as HTMLElement).focus();
What are the steps to reproduce?
In IE, open dialog without an element having focus, close dialog again.
What is the use-case or motivation for changing an existing behavior?
Which versions of Angular, Material, OS, browsers are affected?
Affected browser: IE11.