JavaScript setTimeout in Object

Question

I am trying to give an object a countdown timer and when the countdown is down it should call a function which removes this object from an array.

array = [];

var object = {
    'name' : 'user',
    'limit' : function() {
         setTimeout(destroyMe(this),10000);
    }
}

array.push(object);

var destroyMe = function(obj) {
    array.remove(obj);
}

I know that there could a problem with the this but the timeout function doesnt work at all not even like this:

var object = {
    'name' : 'user',
    'limit' : function() {
               setTimeout(console.log("dd"),3000);
            }
}

Maybe someone can tell me the issue with my version of the setTimeout. thx

[].remove? Never heard of it. And you need to do a array[0].limit() to initiate the countdown. — Salman Arshad
– Salman Arshad, Commented Dec 30, 2012 at 23:20

Lee Taylor · Accepted Answer · 2012-12-30 23:18:14Z

7

setTimeout takes a reference to a function. The code you have is calling the function.

This should be changed to:

var object = 
{
    'name' : 'user',
    'limit' : function() 
    {
        setTimeout(function() { destroyMe(this); }, 10000);
    }
}

(You may have issues using this in this context, try it!)

var object = 
{
    'name' : 'user',
    'limit' : function() 
    {
        setTimeout( function() { console.log("dd"); },3000);
    }
}

answered Dec 30, 2012 at 23:18

Lee Taylor

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11 Comments

ThiefMaster Over a year ago

this will be the global object. He needs to use some other variable pointing to the correct object.

Salman Arshad Over a year ago

first thing's first, call array[0].limit(); somewhere.

user1354743 Over a year ago

I was hoping that the Timout function would call itself after 3 seconds! But it doesnt if i use the code above!

Felix Kling Over a year ago

@user1354743: Just put the setTimeout call after the object.

Lee Taylor Over a year ago

@user1354743 - No, that won't work. You're calling the function, not passing a reference to a function.

|

Peter Olson · Accepted Answer · 2012-12-30 23:18:44Z

1

You need to pass a function to setTimeout, not a function call.

var object = {
    'name' : 'user',
    'limit' : function() {
         setTimeout(function() { 
             destroyMe(this)
         }, 10000);
    }
};

As you already know, the this probably doesn't do what you are expecting. Replacing destroyMe(this) with console.log("dd") should result in a behavior that you would expect.

answered Dec 30, 2012 at 23:18

Peter Olson

144k49 gold badges209 silver badges249 bronze badges

Comments

Community · Accepted Answer · 2017-05-23 12:12:33Z

1

setTimeout either takes a callback (a function, not a function call with arguments) or code in quotes. However, as noted in this question, passing a string is only allowed for historical reasons--there aren't any good reasons for doing it in practice.

But, for completeness sake, one way to do what you want is:

var object = {
    'name' : 'user',
    'limit' : function() {
               setTimeout('console.log("dd")', 3000);
            }
}

edited May 23, 2017 at 12:12

CommunityBot

11 silver badge

answered Dec 30, 2012 at 23:23

Robz

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2 Comments

ThiefMaster Over a year ago

Please do not suggest passing a string. Ever. There is just not a single acceptable reason to do pass a string instead of a function. Besides that he needs this to be preserved.

alex Over a year ago

If mentioning the string passing, you must IMO also warn that it's a pretty terrible way to do things.

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