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If I have a function like the following:
function catchUndefinedFunctionCall( name, arguments )
{
alert( name + ' is not defined' );
}
and I do something silly like
foo( 'bar' );
when foo isn't defined, is there some way I can have my catch function called, with name being 'foo' and arguments being an array containing 'bar'?
982
You can use the typeof to determine the type of the unevaluated operand. It will return the type of operand in a string. You can use "===", if you know they are equal value and equal type.
myVariable is declared and not yet assigned with a value. Accessing the variable evaluates to undefined . An efficient approach to solve the troubles of uninitialized variables is whenever possible assign an initial value. The less the variable exists in an uninitialized state, the better.
The typeof operator for undefined value returns undefined . Hence, you can check the undefined value using typeof operator. Also, null values are checked using the === operator. Note: We cannot use the typeof operator for null as it returns object .
There is in Mozilla Javascript 1.5 anyway (it's nonstandard).
Check this out:
var myObj = {
foo: function () {
alert('foo!');
}
, __noSuchMethod__: function (id, args) {
alert('Oh no! '+id+' is not here to take care of your parameter/s ('+args+')');
}
}
myObj.foo();
myObj.bar('baz', 'bork'); // => Oh no! bar is not here to take care of your parameter/s (baz,bork)
Pretty cool. Read more at https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Global_Objects/Object/NoSuchMethod
88
try {
foo();
}
catch(e) {
callUndefinedFunctionCatcher(e.arguments);
}
UPDATED
passing e.arguments to your function will give you what you tried to pass originally.
31
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