Node util.inherits and this issue

Question

I am trying to resolve a 'this problem' in a Node server. If I don't replace the following worker.stuff with worker.stuff.bind(worker) it doesn't work.

Is there a way to add the bind in the Worker Class itself? Using it every time I call the function is boring.

Here is the server:

var app = require("express")()
    , Worker = require('./worker')
    , worker = new Worker();

app.get("/stuff", worker.stuff);

worker.on('done', function () {
    console.log('done')
});

app.listen(3000);

Here is the worker:

function Worker(options) {}

require('util').inherits(Worker, require('events').EventEmitter);

Worker.prototype.stuff = function (req, res) {
    this.emit('done');
    res.send();
}

module.exports = Worker;

See http://stackoverflow.com/questions/2701987/javascript-function-binding-this-keyword-is-lost-after-assignment. — Trevor Dixon, Nov 27 '13 at 18:36

score 2 · Accepted Answer · answered Nov 27 '13 at 18:59

2

Here's the best I can think of:

function Worker(options) {
    var self = this;

    this.stuff = function (req, res) {
        self.emit('done');
        res.send();
    }
}

require('util').inherits(Worker, require('events').EventEmitter);

module.exports = Worker;

Define all your methods inside the constructor and refer to the closured self instead of this.

I'd probably bite the bullet and use bind as necessary.

answered Nov 27 '13 at 18:59

Trevor Dixon

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This code is ok, but, the `stuff` method is not in the Worker's prototype, no? – yves amsellem Dec 02 '13 at 14:04
No, it isn't in the prototype. – Trevor Dixon Dec 02 '13 at 16:20
Any idea to have both? Binding this and adding methods to the prototype? Thanks. – yves amsellem Dec 02 '13 at 16:23

Node util.inherits and this issue

1 Answers1