The code either invoked one of the Function prototype methods on an object that was not a Function object, or it used an object in a function call context. For example, the following code produces this error because mysample is not a function.
var mysample = new Object(); // Create a new object called "mysample". var x = mysample(); // Try and call mysample as if it were a function.
To correct this error
Only call Function prototype methods on Function objects.
Ensure that the function call operator () calls functions only.