how do you check if an object exists

[toptomato]

Hi,
i'm trying to check if a certain button exists on the page.

i've both of these and they always return false,
uggg....one of those days,....the simplest things..!

if(document.getElementById['testdiv']) {
    alert('it exists');
    //do something
        } else {
    alert('it does not exist');
    //do something else
    } 

i've also tried simply,

if('testdiv') {} 

i also put at the bottom of the page so everything was loaded and also inside of a

$(document).ready(function() { 

[captainscall]

try

myobject = document.getElementById('testdiv');
if (typeof myobject != 'undefined')
{ // this means it exists and has a defined value}
else
{ // this means the type of your object was undefined. i.e. doesn't exist or has no value assigned to it }

[Kever]

When you use document.getElementById on a non existing ID it returns 'null', not 'undefined'.

if(document.getElementById('testdiv') != null) { 
  // exists
} else { 
  // doesn't exist
}

[nap0leon]

The error is that you are using ['testdiv'] instead of ('testdiv')

Change your square brackets to parenthesis and it works fine:

if(document.getElementById('testdiv')) {
    alert('it exists');
    //do something
        } else {
    alert('it does not exist');
    //do something else
    }

[toptomato]

crimeny!!, thanks all! much appreciated