Is there a better way instead of adding values of arrays up using a generator function as closure?

var sumArrays = function(){

  var sum = 0;

  return function*(){

    while(true){

      var array = yield sum;

      if(array.__proto__.constructor === Array){

        sum += array.reduce(function(val,val2){ return val+val2; });

      }

      else sum=0;

    }

  };

};



var gen = sumArrays();

// is this step required to make a generator or could it be done at least differently to spare yourself from doing this step?

gen = gen();



// sum some values of arrays up

console.log('sum: ',gen.next()); // Object { value=0,  done=false}

console.log('sum: ',gen.next([1,2,3,4])); // Object { value=10,  done=false}

console.log('sum: ',gen.next([6,7])); // Object { value=23,  done=false}



// reset values

console.log('sum: ',gen.next(false)); // Object { value=0,  done=false}

console.log('sum: ',gen.next([5])); // Object { value=5,  done=false}