Question

var tests = [1, 4, 3];
for(const test of tests){
  test += 1;
  console.log(test);
}

-我们得到const的类型错误b / c

function average(...nums){
  let sum = 0;
  let counter = 0;
  for(const num of nums){
    sum += num;
    counter++;
  }
  return sum / counter;
}

console.log(average(5, 5));

-为什么由于再次使用const而在这里没有类型错误

Answer 1

因为您要在第一个而不是第二个中重新分配给常量。您将print('Welcome to Rock, Paper, and Scissors. You know the rules already. But, we will play for as long as you want. If you win more rounds, then you survive. If I win though, well... you already know.') while True: w = input('Choose a weapon(r for rock, p for paper, s for scissors, q for quit)!: ').lower() print("W: ", w) if w == 'q': break elif w == 'r' or w == 'p' or w == 's': if game(w): memory(w, fingers) respond(numrock, numpaper, numscissors) hand1(fingers) else: print("Incorrect Option! Please try again.") continue更改为test是非法的，而您从未更改过test += 1。如果您第二次尝试num，则会遇到同样的问题。

Answer 2

我认为您对要更改哪个变量有些困惑。第一个您要更改const test的值，但是在第二个示例中，您要更改let sum

的值

sum += num;与sum = sum + num相同，num保持不变

test += 1;与test = test + 1

为什么在全局范围的for-of循环中使用const会引发TypeError，但在函数内却起作用？

2 个答案: