When using the v8 library or NAN for C++ addon modules, you want to convert the array in Node.js to the std::vector in C++.

Table of Contents

• Given problem
• Solution

1. Given problem

You will have wrong result in std::vector when using the push_back() function.

For example:

In Javascript, arr = [1, 2, 3, 4, 5]

But the below v8, or NAN, you will have: std::vector<int> vect = {0, 0, 0, 0, 0, 1, 2, 3, 4, 5};

I think that the problem can be caused by the asynchronous of Javascript.

2. Solution

You can use the basic array in C++.

Code:

...

Local<Array> array = Local<Array>::Cast(args[0]);

...

unsigned int length = array->Length();
std::vector<double> vect(length);
double* resArr = new double[length];
for (unsigned int i = 0; i < length; ++i)
{
    if (array->Has(i))
    {
        Local<Value> v = array->Get(i);
        if (!v->IsNumber()) 
        {
            return;
        }

		double value = v->NumberValue();
        vect[i] = value;
        resArr[i] = value;		
    }
	else
	{
		return;
	}
}

Thanks for your reading.