The Screen interface represents a screen, usually the one on which the current window is being rendered.
The Selection.collapseToEnd() method collapses the selection to the end of the last range in the selection.  If the content of the selection is focused and editable, the caret will blink there.
The Selection.collapseToStart() method collapses the selection to the start of the first range in the selection.  If the content of the selection is focused and editable, the caret will blink there.
The Selection.deleteFromDocument() method deletes the actual text being represented by a selection object from the document's DOM.
The Selection.extend() method moves the focus of the selection to a specified point. The anchor of the selection does not move. The selection will be from the anchor to the new focus regardless of direction.
The Selection.getRangeAt() method returns a range object representing one of the ranges currently selected.
The Selection.removeRange() method removes a range from the selection.