Adding a mutation to a Data Sync client

Prerequisites

You have Node.js and npm installed.
You have completed the Queries section and the server is still running.

Procedure

Modify the client application to perform the mutation:

src/index.js

// gql is a utility function that handles gql queries
import gql from 'graphql-tag';

import { OfflineClient } from '@aerogear/voyager-client';

// connect to the local service.
let config = {
  httpUrl: "http://localhost:4000/graphql",
  wsUrl: "ws://localhost:4000/graphql",
}

async function addPerson() {

  // Actually create the client
  let offlineClient = new OfflineClient(config);
  let client = await offlineClient.init();

  // Execute the mutation
  client.mutate({
      mutation: gql`
       mutation {
         post(name: "John Doe", address: "1 Red Hill") {
           id
         }
       }
       `
    })
    //Print the response of the query
    .then( ({data}) => {
      console.log(data)
    });
}

addPerson();

Build and run the client application.
Browse the client application and check the console output.

It should include an array similar to the following:
```
{
  "data": {
    "post": {
      "id": "person-1"
    }
  }
}
```

Browse http://localhost:4000/graphql and enter the playground query for the addressbook. For example:

{
  addressBook {
    name
    address

}

Results should be similar to:

{
  "data": {
    "addressBook": [
      {
        "name": "Alex Smith",
        "address": "1 Square Place, City"
      },
      {
        "name": "John Doe",
        "address": "1 Red Hill"
      }
    ]
  }
}