js map函数索引不递增

let newArray = array.map(function(currentValue, index, array) {
  // 返回新数组的当前元素
});

let numbers = [1, 2, 3, 4];
let doubled = numbers.map((num, index) => {
  console.log(`Index: ${index}, Value: ${num}`);
  return num * 2;
});
console.log(doubled); // 输出: [2, 4, 6, 8]

let numbers = [1, 2, 3, 4];
let doubled = numbers.map(async (num, index) => {
  await new Promise(resolve => setTimeout(resolve, 100));
  console.log(`Index: ${index}, Value: ${num}`);
  return num * 2;
});

Promise.all(doubled).then(results => {
  console.log(results); // 输出可能是乱序的
});

let numbers = [1, 2, 3, 4];
let doubled = [];

for (let [index, num] of numbers.entries()) {
  await new Promise(resolve => setTimeout(resolve, 100));
  console.log(`Index: ${index}, Value: ${num}`);
  doubled.push(num * 2);
}

console.log(doubled); // 输出: [2, 4, 6, 8]