void collapse(boolean toStart) throws DOMException;
toStart
If this argument is true, the method sets the end point of the range to the same value as the starting point. Otherwise, it sets the starting point to the same value as the end point.
This method sets one boundary point of the range to be the same as the other point. The point to be modified is specified by the toStart argument. After this method returns, the range is said to be "collapsed": it represents a single point within a document and has no content. When a range is collapsed like this, its collapsed property is true.