路径组成
path.dirname(p)
返回路径p所在的目录
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])
返回路径的最后一个部分，即文件名。参数ext为需要截掉的后缀内容
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)
返回路径p的扩展名，从最后一个’.’到字符串的末尾。如果最后一个部分没有’.’，或者路径是以’.’开头，则返回空字符串
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
返回对应平台下的文件分隔符，win下为’’，*nix下为’/’
var path = require('path');console.log(path.sep); // win下为，*nix下为/
console.log('foobarbaz'.split(path.sep)); // [ 'foo', 'bar', 'baz' ]
console.log('foo/bar/baz'.split(path.sep)); // win下返回['foo/bar/baz']，但在*nix系统下会返回['foo','bar','baz']
path.delimiter
返回对应平台下的路径分隔符，win下为’;’，*nix下为’:’
var path = require('path');console.log(path.delimiter); //win下为“;”，*nix下为“:”
console.log(path.sep); // win下为，*nix下为/
规范化
path.normalize(p)
规范化路径，处理冗余的“..”、“.”、“/”字符。发现多个斜杠时，会替换成一个斜杠。当路径末尾包含一个斜杠时，保留。Windows系统使用反斜杠
var path = require('path');console.log(path.normalize('a/b/c/../user/bin'));//abuserbin
console.log(path.normalize('a/b/c///../user/bin/'));//abuserbin
console.log(path.normalize('a/b/c/../../user/bin'));//auserbin
console.log(path.normalize('a/b/c/.././///../user/bin/..'));//auser
console.log(path.normalize('a/b/c/../../user/bin/../../'));//a
console.log(path.normalize('a/../../user/bin/../../'));//..
