# IsCustomFunction

Determine whether a given object is a custom function.

## Method Signature

```
IsCustomFunction(object=[any], type=[string])
```

### Arguments

| Argument | Type     | Required | Description                                                                   | Default |
| -------- | -------- | -------- | ----------------------------------------------------------------------------- | ------- |
| `object` | `any`    | `true`   | The value to test for closure-ness.                                           |         |
| `type`   | `string` | `false`  | Check for a specific type of custom function - `UDF`, `Lambda`, or `Closure`. |         |

## Examples

### isCustomFunction Example

Here we've example to check the given variable is user defined function or not.

[Run Example](https://try.boxlang.io/?code=eJzjSivNSy7JzM9TyK0EMTU0Faq5OItSS0qL8hQMrblqucqLMktSXUpzCzQUMoudS4tL8nPdoHo0oJoUNBU0rbkA0i0ZNg%3D%3D)

```java

function myfunc() {
	return 1;
}
writeDump( isCustomFunction( myfunc ) );

```

Result: YES

### isCustomFunction Example

Here we've example to check the given variable is user defined function or not.

[Run Example](https://try.boxlang.io/?code=eJzLrUwrzUtWsFVQMlKy5iovyixJdSnNLdBQyCx2Li0uyc91A0qXZObnaSjkQpRqKmhacwEABtYSIg%3D%3D)

```java
myfunc = "2";
writeDump( isCustomFunction( myfunc ) );

```

Result: NO

### Additional Examples

[Run Example](https://try.boxlang.io/?code=eJwrL8osSXUpzS3QUMgsdi4tLsnPdSvNSy7JzM%2FTUChKTcwJdXFT0FTQtOYqx6eyoqICoqoktbgEKKxgC9NszRUB5BgS0A%2FTRtimCIgarjSoCMweDU2Fai7OotSS0qI8kHW1SEqArtNQcMyrVCjLz0xRACms5QIAOE1SOA%3D%3D)

```java
writeDump( isCustomFunction( realUDF ) );
writeDump( isCustomFunction( xxx ) );
testFun = realUDF;
X = 1;
writeDump( isCustomFunction( testFun ) );
writeDump( isCustomFunction( X ) );

function realUDF() {
	return 1;
}

function xxx( Any void ) {
}

```

## Related

* [ArrayIsEmpty](/boxlang-language/reference/built-in-functions/decision/arrayisempty.md)
* [arrayIsEmpty](https://github.com/ortus-boxlang/boxlang-docs/blob/v1.x/boxlang-language/reference/built-in-functions/decision/arrayIsEmpty.md)
* [Attempt](/boxlang-language/reference/built-in-functions/decision/attempt.md)
* [IsArray](/boxlang-language/reference/built-in-functions/decision/isarray.md)
* [IsBinary](/boxlang-language/reference/built-in-functions/decision/isbinary.md)
* [IsBoolean](/boxlang-language/reference/built-in-functions/decision/isboolean.md)
* [IsClosure](/boxlang-language/reference/built-in-functions/decision/isclosure.md)
* [IsDate](/boxlang-language/reference/built-in-functions/decision/isdate.md)
* [IsDateObject](/boxlang-language/reference/built-in-functions/decision/isdateobject.md)
* [IsDebugMode](/boxlang-language/reference/built-in-functions/decision/isdebugmode.md)
* [IsDefined](/boxlang-language/reference/built-in-functions/decision/isdefined.md)
* [IsEmpty](/boxlang-language/reference/built-in-functions/decision/isempty.md)
* [IsFileObject](/boxlang-language/reference/built-in-functions/decision/isfileobject.md)
* [IsIPv6](/boxlang-language/reference/built-in-functions/decision/isipv6.md)
* [IsJSON](/boxlang-language/reference/built-in-functions/decision/isjson.md)
* [IsLeapYear](/boxlang-language/reference/built-in-functions/decision/isleapyear.md)
* [IsLocalHost](/boxlang-language/reference/built-in-functions/decision/islocalhost.md)
* [IsNull](/boxlang-language/reference/built-in-functions/decision/isnull.md)
* [IsNumeric](/boxlang-language/reference/built-in-functions/decision/isnumeric.md)
* [IsNumericDate](/boxlang-language/reference/built-in-functions/decision/isnumericdate.md)
* [IsObject](/boxlang-language/reference/built-in-functions/decision/isobject.md)
* [IsQuery](/boxlang-language/reference/built-in-functions/decision/isquery.md)
* [IsSimpleValue](/boxlang-language/reference/built-in-functions/decision/issimplevalue.md)
* [IsStruct](/boxlang-language/reference/built-in-functions/decision/isstruct.md)
* [IsValid](/boxlang-language/reference/built-in-functions/decision/isvalid.md)
* [IsXML](/boxlang-language/reference/built-in-functions/decision/isxml.md)
* [IsXmlAttribute](/boxlang-language/reference/built-in-functions/decision/isxmlattribute.md)
* [IsXMLDoc](/boxlang-language/reference/built-in-functions/decision/isxmldoc.md)
* [IsXMLElem](/boxlang-language/reference/built-in-functions/decision/isxmlelem.md)
* [IsXMLNode](/boxlang-language/reference/built-in-functions/decision/isxmlnode.md)
* [IsXMLRoot](/boxlang-language/reference/built-in-functions/decision/isxmlroot.md)
* [LSIsNumeric](/boxlang-language/reference/built-in-functions/decision/lsisnumeric.md)
* [structIsEmpty](/boxlang-language/reference/built-in-functions/decision/structisempty.md)


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