javascript alert function strange behaviour

Question

So I am learning JavaScript.... I have gone way past this basic stuff in my learning but can't figure out why this wont work:

   function message(){
      alert("message"); 
    }

<button onclick="message()">Click me</button>

On Js Bin all is ok http://jsbin.com/uwutut/1/edit

On Js fiddle the alert is not triggered!! http://jsfiddle.net/vincentieo/D2dxA/

It is the exact same code...copy and paste so no reason why js fiddle is being fussy??

score 4 · Accepted Answer · answered Jul 26 '13 at 18:01

4

The jsfiddle infrastructure puts your code in an event handler for the "load" event if you don't tell it not to. That means that your function is a local function to that handler, so it's not visible globally.

On the left side of the jsfiddle UI, look for a pull-down about where the code goes, and choose "no-wrap (body)". See if that helps.

answered Jul 26 '13 at 18:01

Pointy

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alternatively: `window.message = function(){ alert("message"); };` – Zach Lysobey Jul 26 '13 at 18:04
Yeah, that makes more sense...so jsfiddle is a little more customizable to our needs. That really cleared it up – vincentieo Jul 26 '13 at 18:11

Mehdi Karamosly · Answer 2 · 2013-07-26T18:13:48.577

0

it works perfectly if you move your javascript to your header

http://jsfiddle.net/D2dxA/2/

<head>
<script>
function message(){
  alert("message"); 
}
</script>
</head>

edited Jul 26 '13 at 18:13

answered Jul 26 '13 at 18:04

Mehdi Karamosly

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That function does not require the DOM. The problem was scoping. Wrapping the code in an `onload` callback didn't expose it to the global scope where he was attempting to call it from. – Zach Lysobey Jul 26 '13 at 18:06
Right got it.... assumed jsfiddle would sort that out for me. THANKS for the replies – vincentieo Jul 26 '13 at 18:07
any good tutorials for learning object orientated programming with js?? – vincentieo Jul 26 '13 at 18:08
1

@vincentieo try [eloquent javascript](http://eloquentjavascript.net/chapter8.html) – Zach Lysobey Jul 26 '13 at 18:09

javascript alert function strange behaviour

2 Answers2