// Configures custom dimension to use the custom parameter
// 'dimension_name' for 'GA_MEASUREMENT_ID', where is a number
// representing the index of the custom dimension.
gtag ('config', 'GA_MEASUREMENT_ID', {
'custom_map': {'dimension': 'dimension_name'}
});
// Sends the custom dimension to Google Analytics.
gtag ( 'event', 'any_event_name', {'dimension_name': dimension_value})
