Javascript - 从循环返回值

Question

function findOdd(A) {
  var odd = 0;
  A.forEach(num => {
    A.forEach(num2 => {
      if (num == num2) {
        odd = odd + 1;
      };
    });

    if (odd % 2 == 1) {
      console.log("num = " + num);
      return num;
    }
    odd = 0;
  });
}

var result = findOdd([5, 0, 0, 0, 2, 2, 3, 3, 4, 4]);

console.log(result);

When I try to return num, it is returning as undefined. And if I remove the "return" statement it is printing correctly to the console.

Answer 1

You can't break out of forEach using return and return it. You are not returning anything from your function as return from foreach does not get returned.

You can use for loop to do this.

 function findOdd(A) { var odd = 0; for (let i = 0; i < A.length; i++) { for (let j = 0; j < A.length; j++) { if (A[i] == A[j]) { odd = odd + 1; } } if (odd % 2 == 1) { console.log("num = " + A[i]); return A[i]; } odd = 0; } } var result = findOdd([5, 0, 0, 0, 2, 2, 3, 3, 4, 4]); console.log(result);