method seekToEnd

This method changes the position of the attached stream to be at the end of the stream.

var fileStreamObj = shell.serviceManager.basics.fileStream;
var streamWriterObj = shell.serviceManager.basics.rawStreamWriter;

fileStreamObj.openForWrite("c:\\temp\\test.txt", false, true);
streamWriterObj.stream = fileStreamObj;
streamWriterObj.seekRelative(-4);
streamWriterObj.writeDouble(20.5);
streamWriterObj.seekToEnd();
streamWriterObj.writeDouble(10.5);

fileStreamObj.close();