fs模块

fs模块

读取数据

1. 同步读取数据-> readFileSync

   参数（path，buffer）

const fs = require('fs');

const textIn = fs.readFileSync('./txt/input.txt','utf-8');
console.log(textIn)

2. 异步读取数据 -> readFile

   参数（path,encoding fun, callback）

fs.readFile("./txt/start.txt", "utf-8", (err, data) => {
  console.log(data);
});
console.log("Will read file!");

​ 也可以连续调用

fs.readFile("./txt/start.txt", "utf-8", (err, data1) => {
  fs.readFile(`./txt/${data1}.txt`, "utf-8", (err, data2) => {
    console.log(data2);
  });
});
console.log("Will read file!");

输出数据

1. 同步输出数据-> writeFileSync

   参数（path，content），这里执行两次的话上一次的文件会被覆盖

const textOut = `This is what we know about the avocado: ${textIn}
Create on ${Date.now()}`;

fs.writeFileSync("./txt/output.txt", textOut);
console.log("File written!");

2. 异步输出数据 -> writeFile

   参数（path，content, encoding, callback）

fs.writeFile("./txt/final.txt", `${data1}\n${data2}`, "utf-8", (err) => {
      console.log("your file has been written!");
});