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javascript: can not use global variable in a function, to navigate the dom

Answer 1

+1 A:

Is the getElemebtById executed before the DOM is loaded? (you should wait for domready or onload)

Is it possible that you overwrite the value in some other funtion?

some 2010-10-10 12:33:53

yep...the dom wasn't loaded

bogdan 2010-10-10 13:55:24

declared the variable inside a function executed on onload...thanks

bogdan 2010-10-10 13:57:52

@bogdan: No problem, it's a very common beginners mistake.

some 2010-10-10 16:19:47

Answer 2

A:

It's not a scope problem.

The most likely reason is that the element doesn't exist yet when you create the variable. You have to put the script element that creates the variable after the element that you want to access, as the code will run while the page is loading.

Another alternative is to declare the variable globally, and set it from the onload event that runs after the page has loaded:

<script>

var x;

function init() {
  x = document.getElementById('xxx1');
}

</script>

<body onload="init();">

Guffa 2010-10-10 12:34:40

Answer 3

A:

I think the problem may be that if you declare that variable globally, when that line is evaluated the DOM is not totally loaded and therefore the element is not accessible.

When you declare it in the function, the variable will only be created when you call that function, when the DOM will mostly likely already be fully loaded.

Danilo 2010-10-10 12:34:59

declared the variable inside a function executed on onload...fixed...thanks everyone!

bogdan 2010-10-10 13:59:18

Answer 4

A:

Maybe your page is not fully loaded when you're calling getElementById.

Make sure you create the global variable x when the page has finished loading. Most libraries has a way to handle that, jQuery for example has the "ready"-function. If you dont want to use any libraries, you can always create the variable when the body-element calls the onload-event.

jQuery-style:

$(function(){
    // create X here
})

body onload style:

<body onload="aFunctionThatCreatesYourVariable()">

Jakob 2010-10-10 12:35:12

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javascript: can not use global variable in a function, to navigate the dom

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