- Objective:如何在函数中添加条件语句。变量，数据类型，条件，函数
- Breadcrumb: JS I
# 概念阐释
# 实例
# 相关内容
# 问题
**写出解题思路：**
🌟
- 获取当下年份
```js
function getCurrentYear() {
const date = new Date();
return date.getFullYear();
}
console.log(getCurrentYear());
```
- 将负数改为正数
```js
function makePositive(num) {
return Math.abs(num);
}
console.log(makePositive(-5)); // 输出: 5
```
- [练习题](https://www.codecademy.com/journeys/full-stack-engineer/paths/fscj-22-building-interactive-websites/tracks/fscj-22-javascript-syntax-part-i/modules/fscj-22-practice-javascript-syntax-variables-data-types-conditionals-functions/lessons/javascript-fundamentals-code-challenge/exercises/how-old)
编写一个名为 howOld() 的函数，它有两个数字参数：年龄和年份，并返回在该年龄的人在那一年的年龄是多少（或将是多少）。处理三种不同的情况：
如果年份在未来，应返回以下格式的字符串：
1. 填写年份大于当下年份=未来 ``You will be ${diff} in the year ${year}``
2. 如果填写年份小于出生年份=过去`The year ${year} was ${diff} years before you were born`
3. 如果填写年份在出生后和当前年份之间`You were ${diff} in the year ${year}`
# 问题答案
```js
// Write your function here:
let howOld = (age,year) => {
//总是知道当前年份
let date = new Date();
let currentYear = date.getFullYear();
const bornYear= currentYear - age;
// 计算年龄（包括未出生的负数）
let diff = Math.abs(year - bornYear);
//满足条件,如果填写年份大于当下年份=未来；
//如果填写年份小于出生年份=过去；
//中间段
if(year > currentYear){
return `You will be ${diff} in the year ${year}`
}else if (year < bornYear){
return `The year ${year} was ${diff} years before you were born`
}else {
return `You were ${diff} in the year ${year}`
};
};
// Once your function is written, write function calls to test your code!
console.log(howOld(35,1986));
console.log(howOld(35,2025));
console.log(howOld(35,1993));
```
# 参考资料
- [GPT-获取当前年份](https://chat.openai.com/share/1d1db6d9-de8f-4059-9aca-01cd20ed7fbf): 内置对象参考