Express res.type() Method
What you’ll learn
- How to set response mime type using
res.type(). - How extension-based mime mapping works.
- How to combine type setting with send/json methods.
- How to avoid wrong content-type responses.
Syntax
javascript
res.type(type)1
Send plain text with explicit mime
javascript
app.get('/plain', function (req, res) {
res.type('text/plain');
res.send('Hello from Express');
});2
Use extension shortcut
javascript
app.get('/csv', function (req, res) {
res.type('csv');
res.send('id,name\n1,Mari');
});3
Set HTML type before response
javascript
app.get('/hello-html', function (req, res) {
res.type('html');
res.send('<h1>Hello</h1>');
});⚠️ Common pitfalls
- Set content type before final send to avoid header timing issues.
- Do not assume type is correct when sending uncommon formats without explicitly setting it.
- Use
res.json()for JSON APIs when possible for clearer intent.
❓ FAQ
It sets the Content-Type header for the response.
Yes, extensions like 'json', 'html', or 'png' are supported and mapped to mime types.
Yes, you can pass values like 'application/json' directly.
Use it when you want explicit content-type control before send/end methods.
No, it only sets the header. You still need to send or end the response.
Did you know?
res.type() sets the Content-Type header and accepts extensions like json, html, or full mime values.
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