提供十个JavaScript的算例，包含if，for，while等语句

当然可以，以下是十个简单的JavaScript示例，涵盖if、for、while等常见语句：

1. **基础if语句**:

let num = 5;
if (num > 0) {
  console.log('数是正的');
}

2. **基本for循环**:

for (let i = 0; i < 5; i++) {
  console.log(i);
}

3. **计数到特定数值的for循环**:

for (let j = 1; j <= 10; j *= 2) { // 这里会打印出2的幂
  console.log(j);
}

4. **while循环计算斐波那契数列**:

let a = 0, b = 1;
let fib = 0;
while (fib < 10) {
  console.log(fib);
  [a, b] = [b, a + b];
  fib++;
}

5. **数组元素查找（if嵌套）**:

const array = [1, 2, 3, 4, 5];
if (array.includes(3)) {
  console.log('找到了数字3');
}

6. **条件判断数组长度**:

let arr = [];
if (arr.length === 0) {
  console.log('数组为空');
}

7. **使用switch语句**:

let day = 'Monday';
switch (day) {
  case 'Sunday':
    console.log('休息日');
    break;
  default:
    console.log('工作日');
}

8. **遍历对象属性**:

let person = {name: 'John', age: 30};
for (let key in person) {
  if (person.hasOwnProperty(key)) {
    console.log(key + ': ' + person[key]);
  }
}

9. **递归计算阶乘**:

function factorial(n) {
  if (n == 0 || n == 1) return 1;
  return n * factorial(n - 1);
console.log(factorial(5));
}

10. **异步操作示例（Promise）**:

let promise = new Promise((resolve, reject) => {
  setTimeout(() => resolve('Promise resolved'), 2000);
});

promise.then(val => {
  if (val === 'Promise resolved') {
    console.log('异步操作完成');
  }
});