Thread: how to extract value in custom fields in vantage

how to extract value in custom fields in vantage

I have a custom field called yelp_id. In CSS, it seems to be shown as "listing-custom-field-app_yelp-id" and i can style it.
However I want to extract the value in this field to display in a widget. I already have the code to do this if I hardcode the widget but would like to populate it with the value in this field. Can you provide a sample on how to do this?