javascript - Passing local functionsto setTimeout() - Stack Overflow

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I have written the following function.

function obj()
{
     this.a;
}
obj.prototype.catch = function()
{
    alert('Catched')
}
obj.prototype.do = function()
{
    alert('called');
}

What i need is, to call obj::catch() after obj::do() is called and the call must be performed from inside obj::do() So how to pass the local function of obj to setTimeout

i have tried

obj.prototype.do = function()
 { 
     window.setTimeout('"'+this.catch+'()"',1000);
     alert('called');
 }

It does not worked Then i tried

 obj.prototype.do = function()
 { 
     window.setTimeout('"'+this+'.catch()"',1000);
     alert('called');
 }

which gave me the following error on Chrome console

Uncaught SyntaxError: Unexpected token ILLEGAL

So i tried the following dirty method(is it really dirty ?)

 obj.prototype.do = function()
 { 
     this.pid = randomVal(100);
     window['temp'+this.pid] = this;
     window.setTimeout("temp"+this.pid+".catch();",1000);
     alert('called');
 }
 function randomVal(bound)//returns a random number between 0 and <bound>
 {
       return (Math.floor(Math.random()*(bound)));
 }

That worked.

so why the first two methods not worked.Is there any other way to do the same thing without global variables.. The second method and last method are almost similar .But why am i gettng the error in second method..? The worked code can be found here /

I have written the following function.

function obj()
{
     this.a;
}
obj.prototype.catch = function()
{
    alert('Catched')
}
obj.prototype.do = function()
{
    alert('called');
}

What i need is, to call obj::catch() after obj::do() is called and the call must be performed from inside obj::do() So how to pass the local function of obj to setTimeout

i have tried

obj.prototype.do = function()
 { 
     window.setTimeout('"'+this.catch+'()"',1000);
     alert('called');
 }

It does not worked Then i tried

 obj.prototype.do = function()
 { 
     window.setTimeout('"'+this+'.catch()"',1000);
     alert('called');
 }

which gave me the following error on Chrome console

Uncaught SyntaxError: Unexpected token ILLEGAL

So i tried the following dirty method(is it really dirty ?)

 obj.prototype.do = function()
 { 
     this.pid = randomVal(100);
     window['temp'+this.pid] = this;
     window.setTimeout("temp"+this.pid+".catch();",1000);
     alert('called');
 }
 function randomVal(bound)//returns a random number between 0 and <bound>
 {
       return (Math.floor(Math.random()*(bound)));
 }

That worked.

so why the first two methods not worked.Is there any other way to do the same thing without global variables.. The second method and last method are almost similar .But why am i gettng the error in second method..? The worked code can be found here http://jsfiddle/jXhAs/

• javascript
• settimeout
• local-variables

Share Improve this question Follow asked Apr 17, 2012 at 14:46 Jinu Joseph DanielJinu Joseph Daniel 6,2911717 gold badges6464 silver badges9292 bronze badges

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4 Answers 4

Sorted by: Reset to default 8

Don't pass strings to setTimeout … ever.

var self = this; // Because the scope will change
setTimeout(function () { self.catch() },1000);

Or if you are using JS 1.8.5:

setTimeout(this.catch.bind(this),1000);

You can read more about bind

You should pass a function to setTimeout (not a string):

Example:

var self = this;
setTimeout(function(){
    self.catch();
},1000);

use a closure

obj.prototype.do = function()
{ 
     window.setTimeout((function(that){
        return function(){
            that.catch();
        };
     })(this),1000);
     alert('called');
}

Why go through all of this effort, just pass the function.

function obj() {
    this.a;
}
obj.prototype.
catch = function() {
    alert('Catched')
}
obj.prototype.do = function() {
    setTimeout(this.
    catch, 1000);
}

var test = new obj();
test.do();​

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