My first script … no effect

So record.getFieldValue() accepts a Tap Forms field ID and will return a variable with contents of that field for the currently selected record. In your example, Dem isn’t declared so you need to define it.

On the left panel of the script editor should be a list of fields, click on your “Dem” field (I’m making a guess here) and then the little “ID” button should insert something like:

var dem_id = 'fld-1234';

I see you want to reference a phoneDem field as well, insert an entry for it, I’m going to assume it looks something like this:

var phoneDem_id  = 'fld-4321';

Now you’ve got the variable set up, you can then use this to get the value of the field:

var dem = record.getFieldValue(dem_id);

This gets the value of the field and puts it into the variable dem which you can then check to see if it matches your value:

if (dem == "Yvon Lainé")
{

It looks like you’re trying to set a value back, so to do that you need to use record.setFieldValue. The first parameter is a field ID and the second is the value you want to set. You also need to tell Tap Forms to save your changes as well with document.saveAllChanges():

    record.setFieldValue(phoneDem_id, "06 xx xx xx xx";
    document.saveAllChanges();
}

@cattailnu on the forum has a Tap Forms JavaScript Scripting 101 that might help you get started as well.

Christian, you are very close to the correct answer:

function Phonedemarcheur() {

	var dem_id = 'fld-29c0876542164738814d28440b9c5e5e';
	var phonedem_id = 'fld-33891151ae8b488e9d359fed52f06aab';
	
	var dem = record.getFieldValue(dem_id);

	console.log(dem);

	//	This exits the function before your if() statement. I commented it out.
	//	return dem ;
	
	if (dem == "Yvon Lainé")
	{
		record.setFieldValue(phonedem_id, "06 00 00 00 00");
		document.saveAllChanges();
	}

}

// You have to call the function to run it. I added it.
Phonedemarcheur();