node ES6语法引入无法正常使用，ES5语法才可以使用

[Dr-SummerFlower]

使用作者提供的ES6 import导入无法正常使用，报错为：

TypeError: IP2Region is not a constructor
    at file:///C:/Users/17218/Desktop/getip/app.js:17:23
    at Layer.handle [as handle_request] (C:\Users\17218\Desktop\getip\node_modules\express\lib\router\layer.js:95:5)
    at next (C:\Users\17218\Desktop\getip\node_modules\express\lib\router\route.js:144:13)
    at Route.dispatch (C:\Users\17218\Desktop\getip\node_modules\express\lib\router\route.js:114:3)
    at Layer.handle [as handle_request] (C:\Users\17218\Desktop\getip\node_modules\express\lib\router\layer.js:95:5)
    at C:\Users\17218\Desktop\getip\node_modules\express\lib\router\index.js:284:15
    at Function.process_params (C:\Users\17218\Desktop\getip\node_modules\express\lib\router\index.js:346:12)
    at next (C:\Users\17218\Desktop\getip\node_modules\express\lib\router\index.js:280:10)
    at expressInit (C:\Users\17218\Desktop\getip\node_modules\express\lib\middleware\init.js:40:5)
    at Layer.handle [as handle_request] (C:\Users\17218\Desktop\getip\node_modules\express\lib\router\layer.js:95:5)

代码是这样的

import express from 'express';
import IP2Region from 'ip2region';

const app = express();

app.get('/', (req, res) => {
    let ip = req.headers['x-forwarded-for'] || req.connection.remoteAddress;
    if (ip.includes('::ffff:')){
        ip = ip.split('::ffff:')[1];
    }
    const ip2Region = new IP2Region();
    const ipAdress = ip2Region.search(ip)
    res.send({ip,ipAdress});
});

app.listen(3000, () => {
    console.log('http://localhost:3000');
})

[Dr-SummerFlower]

研究出解决方法了，需要多加一句

import ip2region from 'ip2region';
const IP2Region = ip2region.default;
const query = new IP2Region();
const ipAddress = query.search(ip);

然后就正常了 本人学艺不精，能解释一下原因吗

[yourtion]

因为我在代码是通过 export default 的方式导出，但是又是通过 ts 编译成了 commonjs，所以用的时候就需要加 default。后续我可以优化一下。

https://remarkablemark.org/blog/2020/05/05/typescript-export-commonjs-es6-modules/