How could I update message from difference socket.io event?

Question

I am using the api with difference event channelName1 and channelName2

//...this the realtime record
socket.on(channelName1, message => {
      console.log(channelName1, message1);
      //this return single item list in realtime`[{"price":100,"size":0.001}]`
 });

//realtime snapshot collection of records
socket.on(channelName2, message => {
   console.log(channelName2, message2);
   //this return the collection `[{"price":100,"size":0.01}, {"price":200,"size":0.02} ]`
   $('#live').text(message2)
});

I want to want to update size of message2 if I found the price":100 is present in the collection message2, so the after update message2 will

[{"price":100,"size":0.001}, {"price":200,"size":0.002} ]

anyone could you guide me how I can do this update from channelName1 to ChannelName2 data?

Answer 1

You have to store the single items somewhere and when the collection arrives you need to:

1. Process each item of the collection using map.
2. For each item, try to find it in the stored single items.
3. If found, change the size.

I have also included a record in the collection that cannot be found so you can see what happens there: it remains unchanged.

Ignore the small changes I made to simulate the sockets. Hopefully you can see the big picture of what I'm doing.

Hope this helps and happy coding.

// Stores each single item that arrives.
let singleItems = [];

// ...this is the realtime record.
function socketOn1(channelName1, message1) {
  console.log(channelName1, message1);

  // Store each single item as it arrives.
  singleItems.push(message1[0]);
};

// realtime snapshot collection of records
function socketOn2(channelName2, message2) {
  console.log(channelName2, message2);

  // For each element in the collection, find
  // the same record in the single items and
  // if found, update the price.
  results = message2.map((elem) => {
    found = singleItems.find(
      (single) => single.price === elem.price
    )
    if (found) {
      elem.size = found.size
    }
    return elem
  })

  console.log('results:')
  console.log(results)
};


// This stuff just simulates stuff arriving to sockets.
// You can ignore it if you want. But look at the order
// in which they are called.

let singleItemsMock = [{
    "price": 100,
    "size": 0.01
  },
  {
    "price": 50,
    "size": 0.02
  },
  {
    "price": 25,
    "size": 0.03
  },
  {
    "price": 10,
    "size": 0.04
  }
]

let collectionMock = [{
    "price": 100,
    "size": 0.001
  },
  {
    "price": 50,
    "size": 0.002
  },
  {
    "price": 13,
    "size": 0.005
  }
]

socketOn1(null, [singleItemsMock[0]])
socketOn1(null, [singleItemsMock[1]])
socketOn1(null, [singleItemsMock[2]])
socketOn1(null, [singleItemsMock[3]])

socketOn2(null, collectionMock)