selection | NN n/a IE 4 DOM n/a
The selection object represents zero or more characters that have been either explicitly selected in a document by the user or selected under script control. All actions on the content of a selection are done via a TextRange object, which can be created from the selection object (see the TextRange object). TextRange and selection objects are available in Navigator 4 only in the Win32 environment. The selection object belongs to the document object. Navigator 4 offers script access to the text selected in a document via the document.getSelection( ) method. In all browsers, be aware that clicking on buttons deselects the current text selection. Therefore, all scripted action involving selections must be triggered by select events or functions invoked by a timer (see the window.setTimeout( ) method description in ).
Object Model Reference
IE | document.selection

type | NN n/a IE 4 DOM n/a
| Read-only
Whether the current selection object has one or more characters selected or is merely an insertion point.
Example
    if (document.selection.type == "Text") {
        ...
    }
Value Either of two constant values (as a string): None | Text.
Default | None.

clear( ) | NN n/a IE 4 DOM n/a
Deletes the content of the current selection in a document. For example, the event handler in the following tag deletes any selected text of the P element two seconds after the user starts making the selection:
    <P onSelectStart="setTimeout('document.selection.clear( )',2000)">
Returned Value None.
Parameters None.

createRange( ) | NN n/a IE 4 DOM n/a
Creates a TextRange object from the current selection object. After a statement like the following:
    var myRange = document.selection.createRange( )
scripts can then act on the content of the selected text.
Returned Value TextRange object.
Parameters None.

empty( ) | NN n/a IE 4 DOM n/a
Deselects the current selection and sets the selection object's type property to None. There is no change to the content that had been selected.
Returned Value None.
Parameters None.