javascript scope issue with "this" [duplicate]

Question

Here is my code:

var timer = 
{
    i: "Hello",

    start: function()
    {       
        var self = this;             
        window.setInterval(self.tick, 1000);     
    },

    tick: function()
    {
        console.log(this.i);
    }       
}

timer.start();

Why the javascript console displays undefined?

Because this in JavaScript works differently than in most other languages. See stackoverflow.com/questions/15858507/javascript-binding-issue . — user1233508
– user1233508, Commented Apr 7, 2013 at 8:00

CD.. · Accepted Answer · 2013-04-07 08:00:40Z

3

Your passing a reference to tick, but not the scope. try:

start: function(){       
    var self = this;             
    window.setInterval(function(){self.tick();}, 1000);     
}

Or use bind (look at the browser compatibility first)

answered Apr 7, 2013 at 8:00

CD..

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Comments

Elger Mensonides · Accepted Answer · 2013-04-07 08:00:51Z

2

change this.i to timer.i

Or use an object declaration like

function timer() {
var self = this;
.. etc.

answered Apr 7, 2013 at 8:00

Elger Mensonides

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Comments

Sushil · Accepted Answer · 2013-04-07 08:02:04Z

1

suggest change window.setInterval(self.tick, 1000); to

window.setInterval(self.tick.bind(self), 1000);

answered Apr 7, 2013 at 8:02

Sushil

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