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Message |
swz
Joined: 11 Feb 2008
Posts: 3
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 Posted: Fri Mar 07, 2008 2:03 am Limit the parameters that can be passed to a function |
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Hi,
is there a way to limit what can be passed as an argument in a function?
For example:
| Code: |
function myFunction (type)
{
//do something;
} |
I want type to be either a predefined str1 or str2. |
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ogsolution
Joined: 26 Dec 2007
Posts: 144
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| Posted: Fri Mar 07, 2008 2:19 am |
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something like this?
| Code: |
<script type="text/javascript">
var a = "abc";
function action(type){
alert(type);
}
action(a);
</script>
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kanenas
Joined: 14 Dec 2004
Posts: 191
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| Posted: Sun Mar 16, 2008 1:23 am Test for object type |
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As javascript is weakly typed, you'll have to enforce argument type yourself, something like:
| Code: |
function isa(obj, type) {
if (typeof(obj) == type
|| obj.constructor == type)
{
return true;
}
return false;
}
function foo(arg) {
if (!(isa(arg, str1) || isa(arg, str2))) {
throw({what: "Argument of 'foo(arg)' must be a str1 or str2.",
argument: arg});
}
// process arg
} |
Note that my solution isn't compatible with inheritance. In particular, the 'isa' function fails when obj's class inherits; the types it fails on depends on the javascript implementation. Fixing 'isa' depends on how you implement inheritance. |
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