javascript type error: Cannot call method 'setAttribute' of null

Question

I'm trying to change the value of a button from 'send' to 'sending' when it's clicked.

I get the error above called on this line:

document.getElementById("submin_btn").setAttribute("value","Sending...");

What's the problem?

It means there is not element with id `submin_btn`, looks like a typo `submit_btn` — Arun P Johny, Apr 26 '13 at 03:33
I imagine you meant to type `submit_btn`. `submin_btn` probably doesn't exist. — Hunter McMillen, Apr 26 '13 at 03:33
In your browser console type `document.getElementById("submin_btn")` and see whether it is returning a value — Arun P Johny, Apr 26 '13 at 03:46
The problem is that the element is not found. I would double check the id and make sure the element is present at the time of calling the above line — TGH, Apr 26 '13 at 03:34

score 0 · Accepted Answer · answered Apr 26 '13 at 03:47

getElementById returns null if it can't find an element with the supplied ID. A more robust method (i.e. one that wont throw errors) is:

var button = document.getElementById("submit_btn"); // spelling of "submin_btn"?
if (button) button.value = "Sending...";

However, if the button is in a form, likely you will not see the value change in some if not most browsers. When a form submits (or navigation away from the current page begins) they cease updating the visible DOM (likely they figure "what's the point?").

javascript type error: Cannot call method 'setAttribute' of null

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