Call a function in another function

Question

I have a function publicRooms to display public discussions that are on the server. I want to use this data for another function I created addNewMessageNewThread:

matrixClient.publicRooms(function(err, data) {
  console.log("Public Rooms: %s", JSON.stringify(data));
  console.log("data", data.chunk[0].aliases[0]);

  this.addNewMessageNewThread({
    'id': 'paul',
    'author': 'Paul Manip',
    'body': '  ?'
  });
});

Off when I do that, he tells me he does not know this function :

ERROR TypeError: Cannot read property 'addNewMessageNewThread' of undefined

And when I test this function outside the function, it works

///////////EDIT//////////////

This is my function addNewMessageNewThread() :

addNewMessageNewThread(objMessage: any): void {

    const newUser: User      = new User(objMessage.author, objMessage.site);
    const newThread: Thread = new Thread(objMessage.id, [newUser],objMessage.title);
    const newMessage = new Message(objMessage);

    objMessage.date = moment().toDate();

    newThread.arrayMessages.push(newMessage);
    newThread.messages = Observable.of(newThread.arrayMessages);

    newThread.lastMessage = newMessage;

    objMessage.thread = newThread;
    this.addThread(newThread);
}

What does addNewMessageNewThread() do? Is it by any chance asynchronous? — Reinstate Monica Cellio
– Reinstate Monica Cellio, Commented Nov 16, 2017 at 10:10

yuantonito · Accepted Answer · 2017-11-16 10:11:54Z

You should pass the context this:

matrixClient.publicRooms(function(err, data) {
  console.log("Public Rooms: %s", JSON.stringify(data));
  console.log("data", data.chunk[0].aliases[0]);

  this.addNewMessageNewThread({
    'id': 'paul',
    'author': 'Paul Manip',
    'body': '  ?'
  });
}, this);

Or use arrow function to use the parent context:

matrixClient.publicRooms((err, data) => {
  console.log("Public Rooms: %s", JSON.stringify(data));
  console.log("data", data.chunk[0].aliases[0]);

  this.addNewMessageNewThread({
    'id': 'paul',
    'author': 'Paul Manip',
    'body': '  ?'
  });
});

hsz · Accepted Answer · 2017-11-16 10:10:25Z

0

Instrad of calling this.addNewMessageNewThread try with matrixClient.addNewMessageNewThread.

this reffers to the callback's context.

If this addNewMessageNewThread doesn't belong to the matrixClient (guessing), before calling matrixClient.publicRooms(), assing:

var that = this;

And use that inside callback instead of this.

answered Nov 16, 2017 at 10:10

hsz

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