I am new to Javascript. I am facing a problem with global variables. I can't figure out that why the global variables are not working as the code looks ok. Please Help me solve this problem. I will breifly explain the code first.I have some text on a page which changes to text field when clicked. When I define the variables inside the functions body the code starts working fine. When these variables are defined globally as in the following code, the console displays this error: the variable is not defined. Here my code:
<!DOCTYPE HTML>
<html>
<head>
<title>Span to Text Box - Demo - DOM</title>
<script type="text/javascript" language="javascript">
var textNode = document.getElementById('text');
var textValue = textNode.firstChild.nodeValue;
var textboxNode = document.getElementById('textbox');
var doneButton = document.getElementById('done');
function change()
{
textboxNode.setAttribute('value', textValue);
textNode.style.display = 'none';
textboxNode.setAttribute('type','text');
doneButton.setAttribute('type','button');
}
function changeBack()
{
textNode.firstChild.nodeValue = textboxNode.value;
textNode.style.display = 'block';
textboxNode.setAttribute('type', 'hidden');
doneButton.setAttribute('type','hidden');
}
</script>
</head>
<body>
<p id="text" onClick="change()">Click me!</p>
<form onSubmit="return false;">
<input type="hidden" id="textbox" />
<input type="hidden" id="done" onClick="changeBack()" value="Done" />
</form>
</body>
</html>
Please Help! Thanks in Advance.
I am new to Javascript. I am facing a problem with global variables. I can't figure out that why the global variables are not working as the code looks ok. Please Help me solve this problem. I will breifly explain the code first.I have some text on a page which changes to text field when clicked. When I define the variables inside the functions body the code starts working fine. When these variables are defined globally as in the following code, the console displays this error: the variable is not defined. Here my code:
<!DOCTYPE HTML>
<html>
<head>
<title>Span to Text Box - Demo - DOM</title>
<script type="text/javascript" language="javascript">
var textNode = document.getElementById('text');
var textValue = textNode.firstChild.nodeValue;
var textboxNode = document.getElementById('textbox');
var doneButton = document.getElementById('done');
function change()
{
textboxNode.setAttribute('value', textValue);
textNode.style.display = 'none';
textboxNode.setAttribute('type','text');
doneButton.setAttribute('type','button');
}
function changeBack()
{
textNode.firstChild.nodeValue = textboxNode.value;
textNode.style.display = 'block';
textboxNode.setAttribute('type', 'hidden');
doneButton.setAttribute('type','hidden');
}
</script>
</head>
<body>
<p id="text" onClick="change()">Click me!</p>
<form onSubmit="return false;">
<input type="hidden" id="textbox" />
<input type="hidden" id="done" onClick="changeBack()" value="Done" />
</form>
</body>
</html>
Please Help! Thanks in Advance.
Share Improve this question edited Nov 26, 2011 at 17:49 Zoidberg 10.3k2 gold badges33 silver badges53 bronze badges asked Nov 26, 2011 at 17:39 Naeem Ul WahhabNaeem Ul Wahhab 2,4954 gold badges35 silver badges61 bronze badges 3- 1 While not directly related to your question, please don't use global JavaScript variables like this - but make sure they're namespaced. More details at blogger.ziesemer./2007/10/… . – ziesemer Commented Nov 26, 2011 at 18:37
- 1 @ziesemer thanks I have read the article you remended – Naeem Ul Wahhab Commented Nov 27, 2011 at 8:33
- WHAT SHOULD EVERY JAVA-SCRIPT PROGRAMMER KNOW? I want to share this most useful post with all my Freinds here. Here is the Link: stackoverflow./q/2628672/1067051 – Naeem Ul Wahhab Commented Nov 30, 2011 at 15:19
2 Answers
Reset to default 5As Adam said, the issue is that you are running javascript on the document before the document has been loaded. There are a number of ways to fix this, but the simplest is to just move your javascript code to the end of the body so the document has already been parsed and is ready before your code runs like this:
<!DOCTYPE HTML>
<html>
<head>
<title>Span to Text Box - Demo - DOM</title>
</head>
<body>
<p id="text" onClick="change()">Click me!</p>
<form onSubmit="return false;">
<input type="hidden" id="textbox" />
<input type="hidden" id="done" onClick="changeBack()" value="Done" />
</form>
<script type="text/javascript" language="javascript">
var textNode = document.getElementById('text');
var textValue = textNode.firstChild.nodeValue;
var textboxNode = document.getElementById('textbox');
var doneButton = document.getElementById('done');
function change()
{
textboxNode.setAttribute('value', textValue);
textNode.style.display = 'none';
textboxNode.setAttribute('type','text');
doneButton.setAttribute('type','button');
}
function changeBack()
{
textNode.firstChild.nodeValue = textboxNode.value;
textNode.style.display = 'block';
textboxNode.setAttribute('type', 'hidden');
doneButton.setAttribute('type','hidden');
}
</script>
</body>
</html>
The error is likely caused by grabbing DOM nodes before they're ready:
var textNode = document.getElementById('text');
This is likely returning either null or undefined since that DOM element hasn't been created yet.
Putting this script at the end of your body should solve your problem.
Or, if you'd like to use jQuery, you can do all this in
$(document).ready(function() {
var textNode = document.getElementById('text');
}