Global Properties
18 May 2010 |
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In When is a global variable not a variable?, Andrew Hedges discusses the difference between variables and global properties.
Try running this example:
try {
// The alert will display undefined
alert(a);
}
catch (e) {
// Not executed
alert(e);
}
var a = 10;
try {
alert(b);
}
catch (e) {
// The alert will display a reference error
alert(e);
}
b = 10;
Removing var actually creates a global property. The distinction is slight, but worth being aware of:
The biggest difference between the two is that variables can’t be deleted using the delete statement. Properties can.
Most people can work safely without ever being aware of this underlying behaviour, but it’s an interesting point.
