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Asked: 2026-05-26T06:54:30+00:00

I am having problems decoding UTF-8 strings in POST data when using the Node.JS

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I am having problems decoding UTF-8 strings in POST data when using the Node.JS web server.

See this complete testcase:

require("http").createServer(function(request, response) {

  if (request.method != "POST") {

    response.writeHead(200, {'Content-Type': 'text/html; charset=utf-8'});
    response.end('<html>'+
      '<head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head>'+
      '<body>'+
      '<form method="post">'+
      '<input name="test" value="Grüße!"><input type="submit">'+
      '</form></body></html>');

  } else {

    console.log("CONTENT TYPE=",request.headers['content-type']);

    var body="";
    request.on('data', function (data) {
      body += data;
    });

    request.on('end', function () {
      console.log("POST BODY=",body);

      response.writeHead(200, {'Content-Type': 'text/plain; charset=utf-8'});
      response.end("POST DATA:\n"+body+"\n---\nUNESCAPED:\n"+unescape(body)+
        "\n---\nHARDCODED: Grüße!");
    });

  }

}).listen(11180);

This is a standalone web server that listens on port 11180 and sends a HTML page with a simple form that contains an input field with special characters. POSTing that form to the server will echo it’s contents in a plain text response.

My problem is that the special charactes are not being displayed properly neither on the console nor in the browser. This is what I see with both FireFox and IE:

POST DATA:
test=Gr%C3%BC%C3%9Fe%21
---
UNESCAPED:
test=GrüÃe!
---
HARDCODED: Grüße!

The last line is a hardcoded string Grüße! that should match the value of the input field (as to verify that it’s not a displaying problem). Obviously the POST data is not interpreted as UTF-8. The same problem happens when using require('querystring') to break the data into fields.

Any clue?

Using Node.JS v0.4.11 on Debian Linux 4, source code is saved in utf-8 charset

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1 Answer

  1. Editorial Team

    The üß UTF-8 characters are not found in the ascii charset, and are being represented by multiple ascii characters.

    According to http://www.w3.org/TR/html4/interact/forms.html#h-17.13.4.1

    The content type “application/x-www-form-urlencoded” is inefficient
    for sending large quantities of binary data or text containing
    non-ASCII characters    . The content type “multipart/form-data” should be
    used for submitting forms that contain files, non-ASCII data, and
    binary data.

    Switching your enctype on the form to multipart <form method="post" enctype="multipart/form-data />" will correctly render the text as the UTF-8 characters. You then have to parse the multipart format. node-formidable seems to be the most popular lib for doing so.

    It’s probably much simpler to use decodeURIComponent() as you mentioned in a comment. Unescape does not handle multibyte characters, and instead represents each byte as its own character, hence the garbling you’re seeing. http://xkr.us/articles/javascript/encode-compare/

    You can also use buffers to change the encoding. Overkill in this case, but if you needed to:

    new Buffer(myString, 'ascii').toString('utf8');
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