如何获取数组中项的索引

function getIndex(arr, target) {
  for (let i = 0; i < arr.length; i++) {
    if (arr[i] === target) {
      return i;
    }
  }
  return -1; // 如果目标项不存在于数组中，返回-1
}

const array = [1, 2, 3, 4, 5];
const target = 3;
const index = getIndex(array, target);
console.log(index); // 输出：2

const array = [1, 2, 3, 4, 5];
const target = 3;
const index = array.indexOf(target);
console.log(index); // 输出：2

const array = [1, 2, 3, 4, 5];
const target = 3;
const index = array.findIndex(item => item === target);
console.log(index); // 输出：2