file

提示

https://nodejs.dev/learn/the-nodejs-fs-module

使用readfile

import * as fs from 'fs'

fs.readFile('/Users/joe/test.txt', 'utf8', (err, data) => {
  if (err) {
    console.error(err);
    return;
  }
  console.log(data);
});

当然也可以使用同步的方式

import * as fs from 'fs'
try {
  const data = fs.readFileSync('/Users/joe/test.txt', 'utf8');
  console.log(data);
} catch (err) {
  console.error(err);
}

使用promise格式的fs

imort * as fsPromises from 'fs/promises'
async function example() {
  try {
    const data = await fsPromises.readFile('/Users/joe/test.txt', { encoding: 'utf8' });
    console.log(data);
  } catch (err) {
    console.log(err);
  }
}
example();

写入文件

import * as fs from 'fs'
const content = 'Some content!';

fs.writeFile('/Users/joe/test.txt', content, err => {
  if (err) {
    console.error(err);
  }
  // file written successfully
});

使用同步的写法

import * as fs from 'fs'
const content = 'Some content!';

try {
  fs.writeFileSync('/Users/joe/test.txt', content);
  // file written successfully
} catch (err) {
  console.error(err);
}

使用promise的写法

imort * as fsPromises from 'fs/promises'

async function example() {
  try {
    const content = 'Some content!';
    await fsPromises.writeFile('/Users/joe/test.txt', content);
  } catch (err) {
    console.log(err);
  }
}
example();

添加写入的flag

fs.writeFile('/Users/joe/test.txt', content, { flag: 'a+' }, err => {});

r+:打开文件(写入或者读取)

在末尾追加

const content = 'Some content!';

fs.appendFile('file.log', content, err => {
  if (err) {
    console.error(err);
  }
  // done!
});

使用promise

async function example() {
  try {
    const content = 'Some content!';
    await fsPromises.appendFile('/Users/joe/test.txt', content);
  } catch (err) {
    console.log(err);
  }
}
example();

写入流

import * as fs from 'fs'
let data = '菜鸟教程官网地址：www.runoob.com';

// 创建一个可以写入的流，写入到文件 output.txt 中
let  writerStream = fs.createWriteStream('output.txt');

// 使用 utf8 编码写入数据
writerStream.write(data,'UTF8');

// 标记文件末尾
writerStream.end();

// 处理流事件 --> finish、error
writerStream.on('finish', function() {
    console.log("写入完成。");
});

writerStream.on('error', function(err){
   console.log(err.stack);
});

console.log("程序执行完毕");