Hello @NG-Helpdesk,
Do you get any errors in the browser console(F12)? Could you please share the screenshot.
There is no separate documentation for it, but the logic is pretty simple. If the field value is stored as an array of objects, you need to specify which object to return, e.g. URL of hyperlink field:
fd.field('Lookup').value.Hyperlink.Url
Single Line of Text field value is stored as a string, so you use this code:
fd.field('Lookup').value.FieldInternalName
You can find more information about getting field values in Managing SharePoint fields with JavaScript article.