Pairwise finished, but without using reduce. (Never mind, found the alternatives)

[Topzie]

My code is accepted, but I didn’t use a reduce method.
Could anyone tell me how I should change my following code and use .reduce() instead of a simple loop in a loop?

function pairwise(arr, arg) {
  var count=0;
  var indexArr=[];
  
    function isInArray(value, array) {
 return array.indexOf(value) > -1;
}
  
  for (var i=0;i<arr.length;i++) {
//    console.log('indexArr checking for i',i, indexArr);

    for (var j=i+1;j<arr.length;j++) {
//      console.log('indexArr checking for j', j , indexArr);
      if(!isInArray(j, indexArr) && !isInArray(i, indexArr)) {
//      console.log(arg, arr[i], arr[j], arr[i]+arr[j]);
      if (arg-arr[i] === arr[j] ) {
        count += (i+j);
        indexArr.push(i,j);

//        console.log('>>> i',i,'j',j, 'arr>>>', arr);
      } 
    }

    }
  }
  return count;
}

pairwise([0, 0, 0, 0, 1, 1], 1);

[Topzie]

Never mind, I found the three solutions. Will have a closr look at them.