Firebase function - 태그 더하기

exports.addDocTag = functions.region("asia-northeast3").firestore

.document("/Documents/{documentId}")

.onWrite((snap, context) => {

const snapshotDescription = snap.data().description;

let reg = /@([\S]+)/igm; //regex

let tags = (commentData['contents'].match(reg) || []).map(e => e.replace(reg, '$1'));

if(tags.length>0){

functions.logger.log("Find tags ", context.params.documentId, tags);

return snap.ref.set({ tags }, { merge: true });}else{return;}

});