document.getElementById problem in JS

[helloise]

i have the code in JS:

if(drop_list.value == "zed-catcher/11")
{
input_box.disabled=false;
var catcher_id = document.getElementById('lpm_service_catcher_id');
catcher_id.value = 11;
}
else
input_box.disabled=true;

how come the line catcher_id.value = 11; is not setting the value to 11????
i get that catcher_id = null????

pleas help
thanks

[johanafm]

Do you get any errors?
Is the if clause true?
What's catcher_id (i.e. I'm not asking about catcher_id.value)?

[helloise]

no i just get that catcher_id is null when i debug with firebug and catcher_id is a var as i declared it
the if is true 🙂

[johanafm]

Yes, catcher_id is a variable, if that line of code is executed. But what does the variable contain? null, a div element, a select element, an input element...?

// This is not necessarily true
if(drop_list.value == "zed-catcher/11")
{
	var catcher_id = document.getElementById('lpm_service_catcher_id');

/* This could be null, a div element, an input element or anything else
 * If you do not get the alert, then this entire if clause is not executed
 * If you get this alert with the string "null", then there is no such element
 * If you get this alert with anything other than  the string
 * "[object HTMLInputElement]", then you have the wrong element
*/
alert(catcher_id);
}