CODEWITHSUNDEEP
javascriptnode.jsevents
Templeton Peck
Templeton Peck

Reputation: 151

Javascript philosophy and events

I'm currently learning NodeJS and Javascript OOP. I need to use a package which uses events handler. But I'm a bit confused with the Javascript philosophy.

I've got a node module which runs like this :

var Module = require("...");
//...
MyObject.prototype.start = function() {
    var myModule = Module();

    myModule.on('connected', function(device) {
        console.log('New device connected !');

        device.on('status', function(status){
            console.log('Device status : '+status);

            device.transfer("someStuff");
        });
    });
}
//...

I would like to call the "transfer()" method of "device" object outside of the "device.on()" events handler. Are there any possibilities ?

Thanks in advance

EDIT : I'm trying this

var Module = require("...");

MyObject.prototype.start = function() {
    var myModule = Module();

    myModule.on('connected', function(device) {
        console.log('New device connected !');

        device.on('status', function(status){
            console.log('Device status : '+status);

            //device.transfer("someStuff");
        });
    });
}

MyObject.prototype.transferData = function(){
    device.transfer("someStuff");
}

Upvotes: 0

Views: 220

Answers (1)

user1726343
user1726343

Reputation:

Since there are multiple methods of MyObject that want to access device, there are a couple of ways you can design this:

  • When MyObject is instantiated, it promisifies the on('connected') callback and stores it as, let's say, devicePromise. All methods on the prototype follow this pattern: return this.devicePromise.then(function (device) { /* do whatever */ }). Any methods that returned values now return promises
  • MyObject cannot be directly instantiated, but can only be created via a factory function that returns a promise of a MyObject instance. This factory function calls on('connected'), and resolves the returned promise with a MyObject instance in which the device property is set. All methods can access this.device

Upvotes: 1

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