运算符在 React JS 中的行为异常

Question

My React app is confusing a "/" string with "+".

  console.log(numbers, signs);

This logs:

Array [ "6", "2" ] Array [ "/" ]

After this I iterate over the arrays and apply the appropriate operator, as shown below:

  for (let e = 1; e < numbers.length; e++) {
    if ((signs[counter] = "+")) {
      newTotal += parseInt(numbers[e]);
      counter += 1;
      console.log(newTotal);
    } else if ((signs[counter] = "-")) {
      newTotal -= parseInt(numbers[e]);
      counter += 1;
      console.log(newTotal);
    } else if ((signs[counter] = "*")) {
      newTotal *= parseInt(numbers[e]);
      counter += 1;
      console.log(newTotal);
    } else if ((signs[counter] = "/")) {
      newTotal = newTotal / parseInt(numbers[e]);
      counter += 1;
      console.log(newTotal);
    }

Every operator works fine, except for "/", which always acts like "+". So the above code returns 8 instead of 3. What gives?

Answer 1

you are assigning signs[counter] to + on top of your if statement. use ===

Answer 2

In order to work properly your code should be like below:

let counter = 0;
for (let e = 1; e < numbers.length; e++) {
    if ((signs[counter] == "+")) {
      newTotal += parseInt(numbers[e]);
      counter += 1;
      console.log(newTotal);
    } else if ((signs[counter] == "-")) {
      newTotal -= parseInt(numbers[e]);
      counter += 1;
      console.log(newTotal);
    } else if ((signs[counter] == "*")) {
      newTotal *= parseInt(numbers[e]);
      counter += 1;
      console.log(newTotal);
    } else if ((signs[counter] == "/")) {
      newTotal = newTotal / parseInt(numbers[e]);
      counter += 1;
      console.log(newTotal);
    }
}