let str = '李泽娟真好看啊'
const fs = require('fs')
fs.writeFile('./word.txt',str,'utf8',(err)=>{//文件写入成功，err的值为null
    if(err === null){
        console.log('文件写入成功');
    }else{
        console.log('写入失败，失败原因：'+err.message);
    }
})