Oups last solution failed in some cases…
But I think that this one is better and simpler (but not fully tested) ..
`// Get repeater field (replace my-repeater-field-key’ with a field key)
repeater = acf.getField(‘my-repeater-field-key’);
// Add a new row
$row = repeater.add();
// Get subfields
let sub_fields=acf.getFields({ parent: $row});
// show sub fields
console.log(sub_fields);
// loop around sub fields and populate them.