Function expected
Either you attempted to invoke one of the Function prototype methods on an object that was not a Function object, or you used an object in a function call context. For example, the following code produces this error because example is not a function.
var example = new Object(); // Create a new object called "example".
var x = example(); // Try and call example as if it were a function.
To correct this error
Only call Function prototype methods on Function objects.
Ensure that you use the function call operator () to call functions only.
See Also
Reference
Function Object (JScript 5.6)
prototype Property (JScript 5.6)