Need help to replace string in html element via class name or element id
I know it's sunday, but my work has no standard working hours.
I'm not sure whether I posted this in the right section but from what I've gathered it has to do with DOM.
I'm not totally new to coding as I code scripts on a daily basis for our servers.
Anyway this project I'm working on is in Joomla and it has a 3rd party extension called Package form maker.
The form maker allows me to create standard html controls, now the specific element or control I am using is a selectbox, but what I need is just something basic to replace a string in the control at runtime via the class name of the html element.
Can someone kindly help me please?
Thanks in advanced