HandleScope scope;

// Check that there are enough arguments. If we access an index that doesn't

// exist, it'll be Undefined().

if (args.Length() < 1) {

// No argument was passed. Throw an exception to alert the user to

// incorrect usage. Alternatively, we could just use 0.

return ThrowException(

Exception::TypeError(String::New("First argument must be a number"))

);

}

// Cast a value to a specific type. See

// http://izs.me/v8-docs/classv8_1_1Value.html for available To*() functions

// and type checking functions. When converting to integer, make sure the

// POD type you use is big enough!

Local<Integer> integer = args[0]->ToInteger();

int32_t seq = integer->Value();

// Also possible in one call. (Don't forget HandleScope, otherwise the

// intermediate Local handle won't be cleaned up!)

// int32_t seq = args[0]->ToInteger()->Value();

// Check for invalid parameter.

if (seq < 0) {

return ThrowException(Exception::TypeError(String::New(

"Fibonacci sequence number must be positive")));

}

// The actual algorithm.

int32_t current = 1;

for (int32_t previous = -1, next = 0, i = 0; i <= seq; i++) {

next = previous + current;

previous = current;

current = next;

}

return scope.Close(Integer::New(current));