Hello :)
if you test this code you can understant easily this feature :
1 - first example
var a = "toto" ;
var b = (a != undefined) ;
if ( b )
{
trace("a exist : " + a) ;
}
2 - second exemple
var a = "toto" ;
if ( a )
{
trace("a exist : " + a) ;
}
You can show the variable a in a conditional expression corresponding with
the "true" value... if the variable is undefined in a conditional expression
the variable is false !
3 - New example :
function test1 ( message )
{
if (message == undefined)
{
message = "empty" ;
}
return message ;
}
trace( test1() ) ;
function test2 ( message:String )
{
if ( !message )
{
message = "empty" ;
}
return message ;
}
trace( test2() ) ;
function test3 ( message:String )
{
message = (message || "empty") ; // if message != undefined ... message
is true the || return message else.. || return "empty"
return message ;
}
trace( test3() ) ;
function test4 (message:String )
{
return (message) ? message : "empty" ; // if message exist and is
true... return message else return "empty"
}
trace( test4() ) ;
...
in a conditional expression, an object used true or false value and not the
primitive value ;) if you use == or < or > or != the variable primitive
value is used...
EKA+ :)
2006/12/22, Steven Sacks | BLITZ <[EMAIL PROTECTED]>:
Saw this recently in code and was surprised that it worked but it's
pretty cool.
a = "foo";
b = "bar";
c = a || b;
trace(c);
-- foo
a = 0;
// or a = "";
// or a = false;
// or a = null;
// or a is undefined
b = "bar";
c = a || b;
trace(c);
-- bar
It will return b if a is an empty string, false, null, 0 or undefined.
Interesting shortcut.
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