Handle POST Form Data with Express JS

Express doesn't handle FormData instances by default. FormData is useful for tasks like uploading a file. You need to use a separate FormData parser, like Formidable, as shown below.

const formidable = require('formidable');

app.post('/upload', function(req, res) {
  const form = new formidable.IncomingForm();
  // Parse `req` and upload all associated files. `files` contains
  // all files that were uploaded with the form.
  form.parse(req, function(err, fields, files) {
    if (err) {
      return res.status(400).json({ error: err.message });
    }
    const [firstFileName] = Object.keys(files);

    res.json({ filename: firstFileName });
  });
});

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More Express Tutorials

• How to Set Response Headers in Express
• What Does `app.use(express.json())` Do in Express?
• Handling POST Requests with Express
• What Does `app.use(express.static())` Do in Express?
• The `app.get()` Function in Express
• The `app.use()` Function in Express
• Express Template Engines