小编Adr*_*cas的帖子

function multipleLetterCount(str){
  var finalObj = {};
  for(var i = 0; i < str.length; i++){
    if(!str[i] in finalObj){
        finalObj[str[i]] = 1;
    } else {
        finalObj[str[i]]++;
    }
}
return finalObj;
}

console.log(multipleLetterCount("SomeWord"));

var nestedArr3 = [[[1,2],[3,4]],[[5,6]]];

function sumTotal() {
  var sum = 0;
  for (var i = 0; i < nestedArr3.length; i++) {
    for (var j = 0; j < nestedArr3[i].length; j++) {
      if (typeof nestedArr3[i][j] === "number") {
        sum += nestedArr3[i][j];
      } else if (Array.isArray(nestedArr3[i][j] === true)) {
        sumTotal(nestedArr3[i][j]);
      }
    }
  }
  return console.log(sum);
}

console.log(sumTotal());