js foreach语法

array.forEach(function(currentValue, index, array) {
  // 执行的操作
});

array.forEach((currentValue, index, array) => {
  // 执行的操作
});

const numbers = [1, 2, 3, 4, 5];

// 使用 forEach 打印每个数字
numbers.forEach((number) => {
  console.log(number);
});

// 使用 forEach 修改数组元素
const doubled = [];
numbers.forEach((number) => {
  doubled.push(number * 2);
});
console.log(doubled); // 输出: [2, 4, 6, 8, 10]

// 使用 forEach 处理异步操作
const asyncTasks = [
  () => new Promise((resolve) => setTimeout(() => resolve('Task 1'), 1000)),
  () => new Promise((resolve) => setTimeout(() => resolve('Task 2'), 500)),
];

async function runTasks() {
  const results = [];
  await Promise.all(asyncTasks.map((task) => task().then((result) => results.push(result))));
  console.log(results); // 输出: ['Task 1', 'Task 2']
}

runTasks();

// 使用 for 循环提前退出
for (let i = 0; i < numbers.length; i++) {
  if (numbers[i] === 3) break;
  console.log(numbers[i]);
}

// 使用 some 提前退出
numbers.some((number) => {
  if (number === 3) return true; // 提前退出
  console.log(number);
  return false;
});

const modifiedNumbers = numbers.map((number) => number * 2);
console.log(modifiedNumbers); // 输出: [2, 4, 6, 8, 10]