我用express 3在node.js中创建了一个文件上传函数。

我想抓取图像的文件扩展名。所以我可以重命名文件,然后附加文件扩展名。

app.post('/upload', function(req, res, next) {
    var is = fs.createReadStream(req.files.upload.path),
        fileExt = '', // I want to get the extension of the image here
        os = fs.createWriteStream('public/images/users/' + req.session.adress + '.' + fileExt);
});

如何在node.js中获得图像的扩展名?


当前回答

const path = require('path');

function getExt(str) {
  const basename = path
    .basename(str)
    // Patch: for hidden files
    // Removes all dots at the beginning of a line
    .replace(/^(\.+)/i, '');

  const firstDot = basename.indexOf('.');
  const lastDot = basename.lastIndexOf('.');
  const extname = path.extname(basename).replace(/(\.[a-z0-9]+).*/i, '$1');

  if (firstDot === lastDot) {
    return extname;
  }

  return basename.slice(firstDot, lastDot) + extname;
}
const files = [
  '/home/charlike/bar/.hidden.tar.gz~',     // ".tar.gz"
  '/home/charlike/bar/file.tar.gz~',        // ".tar.gz"
  '/home/charlike/bar/file.tar.gz+cdf2',    // ".tar.gz"
  '/home/charlike/bar/file.tar.gz?quz=zaz', // ".tar.gz"
];

const fileAndExt = files.map((file) => [ file, getExt(file) ]);

console.log(JSON.stringify(fileAndExt, null, 2));

其他回答

扩展String.prototype的一行代码:

Object.defineProperty(String.prototype, "ext", {get: function(x) {return this.split('.').pop()}})
str = 'fox.fbx';
str.ext

结果:

const path = require('path');

function getExt(str) {
  const basename = path
    .basename(str)
    // Patch: for hidden files
    // Removes all dots at the beginning of a line
    .replace(/^(\.+)/i, '');

  const firstDot = basename.indexOf('.');
  const lastDot = basename.lastIndexOf('.');
  const extname = path.extname(basename).replace(/(\.[a-z0-9]+).*/i, '$1');

  if (firstDot === lastDot) {
    return extname;
  }

  return basename.slice(firstDot, lastDot) + extname;
}
const files = [
  '/home/charlike/bar/.hidden.tar.gz~',     // ".tar.gz"
  '/home/charlike/bar/file.tar.gz~',        // ".tar.gz"
  '/home/charlike/bar/file.tar.gz+cdf2',    // ".tar.gz"
  '/home/charlike/bar/file.tar.gz?quz=zaz', // ".tar.gz"
];

const fileAndExt = files.map((file) => [ file, getExt(file) ]);

console.log(JSON.stringify(fileAndExt, null, 2));
var fileName = req.files.upload.name;

var arr = fileName.split('.');

var extension = arr[length-1];

路径。Extname在大多数情况下都可以。但是,它将包括最后一个.之后的所有内容,包括http请求的查询字符串和散列片段:

var path = require('path')
var extname = path.extname('index.html?username=asdf')
// extname contains '.html?username=asdf'

在这种情况下,你可以尝试这样做:

var regex = /[#\\?]/g; // regex of illegal extension characters
var extname = path.extname('index.html?username=asdf');
var endOfExt = extname.search(regex);
if (endOfExt > -1) {
    extname = extname.substring(0, endOfExt);
}
// extname contains '.html'

请注意,具有多个句点的扩展(例如.tar.gz)在path.extname下根本不起作用。

例如,您可以使用path.parse(path)

const path = require('path');
const { ext } = path.parse('/home/user/dir/file.txt');