Has anyone any idea how in an on change event I can get the text value from a selection field instead of the code?

All I'm trying to do is set the comm_subject to the text of a selection field to add a quick way of setting BUT still allow manual entry into comm_subject if required.

So my new field is comm_qsubject and is a selection but I have for example codes of 2 digits with detailed text, eg SM = Social Media.

If I enter into the OnChange Script on the comm_qsubject : comm_subject.value=comm_qsubject.value; The comm_subject is being set to 'SM'.

All I need to know is how to get 'Social Media' instead...

Thanks