Passing Javascript Array to Flask

I have a function in flask called array that takes in a list and prints out the items in the list:

def array(list):
    string = ""
    for x in list:
        string+= x
    return string

On the client side, I want to pass in a javascript array named str into this array. How would I do that? Here's what I have right now, but Flask isn't reading the added variable. Any ideas?

for (var i = 0; i < response.data.length; i++) {
            console.log(i);

            // str = str + "<br/><b>Pic</b> : <img src='"+ response.data[i].picture +"'/>";

            str[i] = response.data[i].picture;
        }
        window.location = "{{ url_for('array', str=list ) }}";