I have a user script to add a calculation form to a website. The iframe should pull the price (ID lblFcost) and insert this into the SRC of the iframe for the calculation form.

This is the userscript I have and trialled code.

var theDiv = document.getElementById('tblManConNoteMsg');
theDiv.innerHTML = '<iframe id="inlineFrameExample" width="1000" height="1000" src="https://exampleurl.com/tnt-surcharge/?price=" + lblFcost;></iframe>';

Glad of any help.