createNewUsers.js

// I use this js function inside ManageUsers.vue. It maps through an array of user data (jsonData) to call the createUser httpsCallable function.

async createNewUsers () {
      this.loadingNewUsers = true
      var createUser = this.$fb.functions().httpsCallable('createUser')
      let promises = this.jsonData.map(person => {
        // I use quasar uid to create an initial password: https://quasar.dev/quasar-utils/other-utils#Generate-UID
        person.password = uid()
        let jsonDatum = []
        jsonDatum.push(person)
        return createUser({ user: jsonDatum }) // * createUser returns a promise first
          .then(result => {
            console.log('returnedMessage: ', result.data.text)
            let local = result.data.text + ` ${person.email}` 
            // If the returned response (local) starts with error, it is added to an array of error responses.
            if (_.startsWith(local, 'Error')) {
              this.errorMessages.push(local)
            } else {
              console.log('returned message: ', local)
              // successMessages is a local array containing all of the positive responses from firebase. 
              // I display errorMessages and successMessages in the UI so that I know if it worked.
              this.successMessages.push(local)
            }
            this.loading = false
          })
      })
      await Promise.all(promises)
      this.loadingNewUsers = false
    },