前面的話

　　path模塊包含一系列處理和轉換文件路徑的工具集，通過 require(‘path‘) 可用來訪問這個模塊。本文將詳細介紹path模塊

路徑組成

【path.dirname(p)】

　　返回路徑p所在的目錄

var path = require(‘path‘);
console.log(path.dirname(‘/foo/bar/baz/asdf/a.txt‘));  // /foo/bar/baz/asdf
console.log(path.dirname(‘/foo/bar/baz/asdf/‘));  // /foo/bar/baz
console.log(path.dirname(‘C:/test/aaa‘));  //
 
 C:/test

【path.basename(p[, ext])】

　　返回路徑的最後一個部分，即文件名。參數ext為需要截掉的後綴內容　

var path = require(‘path‘);
console.log(path.basename(‘/foo/bar/baz/asdf/a.txt‘));  // a.txt
console.log(path.basename(‘/foo/bar/baz/asdf/a.txt‘,‘.txt‘));  // a
console.log(path.basename(‘/foo/bar/baz/asdf/‘));  // asdf
console.log(path.basename(‘C:/test/aaa‘));  //
 
 aaa

【path.extname(p)】

　　返回路徑p的擴展名，從最後一個‘.‘到字符串的末尾。如果最後一個部分沒有‘.‘，或者路徑是以‘.‘開頭，則返回空字符串

var path = require(‘path‘);
console.log(path.extname(‘/foo/bar/baz/asdf/a.txt‘));  // .txt
console.log(path.extname(‘/foo/bar/baz/asdf/a.txt.b‘));  // .b
console.log(path.extname(‘/foo/bar/baz/asdf/a.‘));  // .
console.log(path.extname(‘C:/test/aaa/.‘));  //
 
 ‘‘
console.log(path.extname(‘C:/test/aaa‘));  // ‘‘

分隔符

【path.sep】

　　返回對應平臺下的文件分隔符，win下為‘\‘，*nix下為‘/‘

var path = require(‘path‘);
console.log(path.sep);  // win下為\，*nix下為/
console.log(‘foo\\bar\\baz‘.split(path.sep));  // [ ‘foo‘, ‘bar‘, ‘baz‘ ]
console.log(‘foo/bar/baz‘.split(path.sep));  // win下返回[‘foo/bar/baz‘]，但在*nix系統下會返回[‘foo‘,‘bar‘,‘baz‘]

【path.delimiter】

　　返回對應平臺下的路徑分隔符，win下為‘;‘，*nix下為‘:‘

var path = require(‘path‘);
console.log(path.delimiter); //win下為“;”，*nix下為“:”
console.log(path.sep);  // win下為\，*nix下為/

規範化

【path.normalize(p)】

　　規範化路徑，處理冗余的“..”、“.”、“/”字符。發現多個斜杠時，會替換成一個斜杠。當路徑末尾包含一個斜杠時，保留。Windows系統使用反斜杠　

var path = require(‘path‘);
console.log(path.normalize(‘a/b/c/../user/bin‘));//a\b\user\bin
console.log(path.normalize(‘a/b/c///../user/bin/‘));//a\b\user\bin\
console.log(path.normalize(‘a/b/c/../../user/bin‘));//a\user\bin
console.log(path.normalize(‘a/b/c/.././///../user/bin/..‘));//a\user
console.log(path.normalize(‘a/b/c/../../user/bin/../../‘));//a\
console.log(path.normalize(‘a/../../user/bin/../../‘));//..\
console.log(path.normalize(‘a/../../user/bin/../../../../‘));//..\..\..\
console.log(path.normalize(‘./a/.././user/bin/./‘));//user\bin\

【path.join([path1], [path2], [...])】

　　將多個路徑結合在一起，並轉換為規範化路徑　

var path = require(‘path‘);
console.log(path.join(‘////./a‘, ‘b////c‘, ‘user/‘));//\a\b\c\user
console.log(path.join(‘a‘, ‘../../‘, ‘user/‘));//..\user\

絕對和相對

【path.resolve([from ...], to)】

　　從源地址 from 到目的地址 to 的絕對路徑，類似在shell裏執行一系列的cd命令

path.resolve(‘foo/bar‘, ‘/tmp/file/‘, ‘..‘, ‘a/../subfile‘)

　　類似於:

cd foo/bar
cd /tmp/file/
cd ..
cd a/../subfile
pwd

　　[註意]如果某個from或to參數是絕對路徑（比如 ‘E:/abc‘，或是以“/”開頭的路徑），則將忽略之前的from參數

var path = require(‘path‘);
console.log(path.resolve(‘.‘, ‘testFiles/..‘, ‘trdLayer‘));//D:\project\trdLayer
console.log(path.resolve(‘..‘, ‘testFiles‘, ‘a.txt‘));//D:\testFiles\a.txt
console.log(path.resolve(‘D:‘, ‘abc‘, ‘D:/a‘));//D:\a
console.log(path.resolve(‘abc‘, ‘ok.gif‘));//D:\project\abc\ok.gif
console.log(path.resolve(‘abc‘, ‘..‘, ‘a/../subfile‘)); //D:\project\subfile

【path.isAbsolute(path)】

　　path是一個絕對路徑(比如 ‘E:/abc‘)，或者是以“/”開頭的路徑，二者都會返回true

var path = require(‘path‘);
console.log(path.isAbsolute(‘../testFiles/secLayer‘));//false
console.log(path.isAbsolute(‘./join.js‘));//false
console.log(path.isAbsolute(‘temp‘));//false
console.log(path.isAbsolute(‘/temp/../..‘));//true
console.log(path.isAbsolute(‘E:/github/nodeAPI/abc/efg‘));//true
console.log(path.isAbsolute(‘///temp123‘));//true

【path.relative(from, to)】

　　獲取從 from 到 to 的相對路徑，可以看作 path.resolve 的相反實現

path.resolve(from, path.relative(from, to)) == path.resolve(to)

var path = require(‘path‘);
console.log(path.relative(‘C:\\\test‘, ‘C:\\\impl\\bbb‘));//..\impl\bbb
console.log(path.relative(‘C:/test/aaa‘, ‘C:/bbb‘));//..\..\bbb
console.log(path.relative(‘C:/test/aaa‘, ‘D:/bbb‘));//D:\bbb

nodeJS之路徑PATH模塊