Type Alias


The callback invoked when converting an object to a particular JavaScript type.


typealias JSObjectConvertToTypeCallback = (JSContextRef?, JSObjectRef?, JSType, UnsafeMutablePointer<JSValueRef?>?) -> JSValueRef?



The execution context to use.


The JSObject to convert.


A JSType specifying the JavaScript type to convert to.


A pointer to a JSValueRef in which to return an exception, if any.

Return Value

The objects's converted value, or NULL if the object was not converted.


If you named your function ConvertToType, you would declare it like this:

JSValueRef ConvertToType(JSContextRef ctx, JSObjectRef object, JSType type, JSValueRef* exception);

If this function returns false, the conversion request forwards to object's parent class chain (which includes the default object class).

This function is only invoked when converting an object to number or string. An object converted to boolean is 'true.' An object converted to object is itself.

See Also


typealias JSObjectCallAsConstructorCallback

The callback invoked when an object is used as a constructor in a 'new' expression.

typealias JSObjectCallAsFunctionCallback

The callback invoked when an object is called as a function.

typealias JSObjectDeletePropertyCallback

The callback invoked when deleting a property.

typealias JSObjectFinalizeCallback

The callback invoked when an object is finalized (prepared for garbage collection). An object may be finalized on any thread.

typealias JSObjectGetPropertyCallback

The callback invoked when getting a property’s value.

typealias JSObjectGetPropertyNamesCallback

The callback invoked when collecting the names of an object’s properties.

typealias JSObjectHasInstanceCallback

hasInstance The callback invoked when an object is used as the target of an 'instanceof' expression.

typealias JSObjectHasPropertyCallback

The callback invoked when determining whether an object has a property.

typealias JSObjectInitializeCallback

The callback invoked when an object is first created.

typealias JSObjectSetPropertyCallback

The callback invoked when setting a property’s value.