Variable scope

ckennerdale · Apr 9, 2002

Can anyone explain why this code writes 'no' in the document when I expect it to write 'yes'

<html>
<head>
<script>
var pressed = 0;
function Test(){

if (document.pressed == 0){
document.write("yes&quot

;
}else{
document.write("no&quot

;
}
}

</script>
</head>
<body onload="Test()">
</body>
</html>

Thanks in advance Caspar Kennerdale
Senior Media Developer

http://www.thetuckshop.com

http://developer.thetuckshop.com

xutopia · Apr 9, 2002

using a . after document makes you access part of the DOM of document.

for example document.write is a method associated with document.

pressed is not a property of the document but a global variable.

when you wrote if (document.pressed) you only checked to see if document had a property or function named pressed.

<html>
<head>
<script>
var pressed = 0;
function Test()
{
if (pressed == 0)
{
document.write("yes&quot

;
}
else
{
document.write("no&quot

;
}
}
</script>
</head>
<body onload="Test()">
</body>
</html> Gary

http://www.xutopia.com

Haran

RnK · Apr 9, 2002

I'm not sure if this fully explains it to you but by removing the 'document' from the equation you'll get 'yes' for your answer. I don't believe global variables are stored as part of the document object, however if you destroy the document you destroy the variables so something in the document retains the variables.

if (pressed == 0){
document.write("yes&quot

;
}else{
document.write("no&quot

;
}

You can see the document properties using the script below.

<script language="javascript" type="text/javascript">
<!--
var str = "";
for(i in document){
str += i+": " + document + "\n";
}
alert(str);
</script>

the same can be done with the properties of the document properties, eventually you'll find the area where the variables are stored.

Hope this helps
RnK

ckennerdale · Apr 9, 2002

Thanks all

I originally tried without the document.

It didnt work at the time- but I think that was browser caching as it works now Caspar Kennerdale
Senior Media Developer

http://www.thetuckshop.com

http://developer.thetuckshop.com

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Variable scope

ckennerdale

Programmer

xutopia

Programmer

RnK

Programmer

ckennerdale

Programmer

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