Convert Firebase Database JSON to Firestore Collections

FirebaseToFirestore.js

    var db = firebase.firestore();
    var content = require("./sourceData.json");

    content &&
      Object.keys(content).forEach(contentKey => {
        const nestedContent = content[contentKey];
        if (typeof nestedContent === "object") {
          Object.keys(nestedContent).forEach(docTitle => {
            firebase
              .firestore()
              .collection(contentKey)
              .doc(docTitle)
              .set(nestedContent[docTitle]);
          });
        }
      });