little error in !"foo", correct like this:
if (!"foo") {
// This will never run.
trace('"foo"');
}
Mike schrieb:
You can actually just use (!var) in most cases.
if (!undefined) {
// This will always run.
trace(undefined);
}
if (!null) {
// This will always run.
trace(null);
}
if (!false) {
// This will always run.
trace(false);
}
if (!0) {
// This will always run.
trace(0);
}
if (!"") {
// This will always run.
trace('""');
}
if (!"".length) {
// This will always run.
trace('"".length');
}
if (!"foo") {
// This will always run.
trace('"foo"');
}
if (![].length) {
// This will never run.
trace("[].length");
}
// Conversely...
if (!"foo".length) {
// This will always run.
trace('"foo".length');
}
if (!true) {
// This will never run.
trace(true);
}
if (!1) {
// This will never run.
trace(1);
}
if (!-1) {
// This will never run.
trace(-1);
}
if (!(Math.random() + 1)) {
// This will never run.
trace("Math.random() + 1");
}
if (!{}) {
// This will never run.
trace("{}");
}
if (![]) {
// This will never run.
trace("[]");
}
--
T. Michael Keesey
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Rifled
Cloaca
Sent: Wednesday, July 19, 2006 8:00 AM
To: Flashcoders mailing list
Subject: [Flashcoders] Difference between null and undefined?
FlashCoders,
I've recently been upgrading some old Flash MX code to Flash 8, and have
been running into issues where properties return 'undefined' instead of
'null'. I seem to recall that undefined was introduced in Flash 7.
I've
always been confused about when something is undefined versus null, so I
always check for both. { (var != undefined && var != null) }
Is there an explanation somewhere regarding the difference between
undefined
and null, and when to expect which? If not, can someone who understands
explain it?
Thanks in advance!
-rc
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http://chattyfig.figleaf.com/mailman/listinfo/flashcoders
Brought to you by Fig Leaf Software
Premier Authorized Adobe Consulting and Training
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