文件路径操作

var path = require(‘path’);

1、查询路径

// 当前文件夹和文件名的完整路径
console.log(__dirname);
console.log(__filename);

// 当前执行目录shell所有位置
console.log(process.cwd());


process.chdir("/");
// /表示shell跑到根目录下
console.log(process.cwd()); 

// /usr/local/bin/node 表示bin目录安装地方
console.log(process.execPath);

2、操作路径

var dir = ["foo", "bar", "baz"];// array
// foo\bar\baz
console.log(dir.join('\\')); // windows
// foo/bar/baz
console.log(dir.join('/'));// mac linux

// if in window it will print '\' but here is '/';
console.log(path.sep); 
// foo/bar/baz
console.log(dir.join(path.sep));

3、环境变量

path.delimiter

// 输出 :
console.log(path.delimiter);
process.env.PATH.split(path.delimiter).forEach(function(dir){
	console.log(dir);
});
console.log(process.env.PATH);

4、返回文件扩展名

path.extname

var fileName = "/foo/bar/baz.txt";
var extension = path.extname(fileName);
// .txt
console.log(extension);

5、返回文件名

path.basename

var fileName = "/foo/bar/baz.txt";
var file = path.basename(fileName)
// baz.txt
console.log(file);

6、返回父文件夹的路径

path.dirname

var fileName = "/foo/bar/baz.txt";
var file1 = path.dirname(fileName);
// /foo/bar
console.log(file1);

7、序列化路径

path.normalize

var dirName = "/foo/bar/.././bar/../../baz";
var normalized = path.normalize(dirName);
// 同样的功能
// var normalized = path.join("/foo/bar", ".././bar", "../..", "/baz");
// /baz
console.log(normalized);

8、相对路径

path.relative

var from = '/foo/bar';
var to = '/baz/biff';
var relative = path.relative(from,to);
// ../../baz/biff
console.log(relative);

9、其它

path.resolve、path.join、path.isAbsolute、path.parse、path.format

// /Users/zhengwenping/works/webServer/nodestudy/foo/bar/baz
// 类似命令行cd一个个执行 执行路径
console.log(path.resolve('../foo/bar','./baz'));

// ../foo/bar/baz 拼路径
console.log(path.join('../foo/bar','./baz'));

// 是否是一个绝对路径isAbsolute
// false true
console.log(path.isAbsolute('./foo/bar'),path.isAbsolute('/foo/bar'));

// 输出路径信息
var parsed = path.parse('/home/user/dir/file.txt');
/*
{ root: '/',
  dir: '/home/user/dir',
  base: 'file.txt',
  ext: '.txt',
  name: 'file' 
}
*/
// console.log(parsed);


// path.format

var pt = path.format({
	dir:'/home/user/dir',
	base:'file.txt'
});
// /home/user/dir/file.txt
console.log(pt);

文件系统操作

var fs = require(“fs”)

接下来就是文件系统 纯JS没法实现 只能调用底层c++/c实现方法

1、判断文件是否存在

fs.exists() and fs.existsSync() return boolean

var path = __dirname + "/filesystem.js";
var existsSync = fs.existsSync(path); // 同步
console.log(existsSync); // true;
var existsSync = fs.exists(path,function(exists){
	console.log(exists); // 异步 true;
})

2、文件属性

fs.stat fs.lstat fs.fstat

fs.stat('./end.jpeg',function(error,stats){
	console.log(stats);
});

// 快捷文件文件图标返回不是实际对应文件大小
fs.lstat('./end.jpeg',function(error,stats){
	console.log(stats);
});

fs.open('./end.jpeg','a',function(error,fd){
	fs.fstat(fd,function(error,stats){
		console.log(stats);
	})
})

/*
{ dev: 16777220,
  mode: 33188,
  nlink: 1,
  uid: 501,
  gid: 20,
  rdev: 0,
  blksize: 4096,
  ino: 22663534,
  size: 1921,
  blocks: 8,
  atime: 2017-02-22T07:22:10.000Z,
  mtime: 2016-10-30T01:10:50.000Z,
  ctime: 2016-11-03T09:23:16.000Z,
  birthtime: 2016-10-30T01:10:50.000Z }
*/

3、读文件内容

fs.readFile fs.readFileSync

var path = __dirname + "/oread.txt";
fs.readFile(path,"utf8",function(error,data){
	if(error) {
		console.error("read error:"+ error.message);
	}else {
		console.log(data);
	}
})

4、写入文件内容

fs.writeFile fs.writeFileSync

var data = "Lorem ipsum dolor sit amet sssss";
fs.writeFile(path, data, function(error) {
	if(error){
		console.log("write error: "+ error.message );
	}else{
		console.log("Successfully wrote" + path);
	}
})

5、重命名

fs.rename

var oldPath = __dirname + "/oread.txt";
var newPath = __dirname + "/read.txt";

fs.rename(oldPath,newPath,function(error){
	if(error) {
		console.error("rename error:" + error.message);
	}else{
		console.log("Successfully renamed the file!");
	}
})

6、新建文件夹

mkdir mkdirSync

var path = __dirname + "/feo";
fs.mkdir(path,function(error){
	
});

7、删除文件

fs.unlink

var path = __dirname + "/foo/txt.js";
fs.unlink(path,function(error){
	if(error){
		console.error("unlink error:"+error.message);
	}
})

8、返回目录下所有文件

fs.readdir() and fs.readdirSync()

var path = process.cwd();
fs.readdir(path, function(error,files){
	console.log(files);
})
/*
[ '.DS_Store',
  'end.jpeg',
  'feo',
  'filesystem.js',
  'foo',
  'read.txt',
  'tmp.js' ]*/

9、删除文件夹

fs.rmdir() rmdirSync()

var path = __dirname + "/feo";
fs.rmdir(path,function(error){
	if(error){
		console.error("unlink error:"+error.message);
	}
})