Logo Questions Linux Laravel Mysql Ubuntu Git Menu
 

How can I set response header on express.js assets

People also ask

Can we set response header?

Select the web site where you want to add the custom HTTP response header. In the web site pane, double-click HTTP Response Headers in the IIS section. In the actions pane, select Add. In the Name box, type the custom HTTP header name.

Which node JS method set a header to the response?

setHeader(name, value) (Added in v0. 4.0) method is an inbuilt application programming interface of the 'http' module which sets a single header value for implicit headers. If this header already exists in the to-be-sent headers, its value will be replaced.


There is at least one middleware on npm for handling CORS in Express: cors. [see @mscdex answer]

This is how to set custom response headers, from the ExpressJS DOC

res.set(field, [value])

Set header field to value

res.set('Content-Type', 'text/plain');

or pass an object to set multiple fields at once.

res.set({
  'Content-Type': 'text/plain',
  'Content-Length': '123',
  'ETag': '12345'
})

Aliased as

res.header(field, [value])

This is so annoying.

Okay if anyone is still having issues or just doesn't want to add another library. All you have to do is place this middle ware line of code before your routes.

Cors Example

app.use((req, res, next) => {
    res.append('Access-Control-Allow-Origin', ['*']);
    res.append('Access-Control-Allow-Methods', 'GET,PUT,POST,DELETE');
    res.append('Access-Control-Allow-Headers', 'Content-Type');
    next();
});

// Express routes
app.get('/api/examples', (req, res)=> {...});

You can do this by using cors. cors will handle your CORS response

var cors = require('cors')

app.use(cors());

Short Answer:

  • res.setHeaders - calls the native Node.js method

  • res.set - sets headers

  • res.headers - an alias to res.set


@klode's answer is right.

However, you are supposed to set another response header to make your header accessible to others.


Example:

First, you add 'page-size' in response header

response.set('page-size', 20);

Then, all you need to do is expose your header

response.set('Access-Control-Expose-Headers', 'page-size')

There is at least one middleware on npm for handling CORS in Express: cors.


You can also add a middleware to add CORS headers, something like this would work:

/**
 * Adds CORS headers to the response
 *
 * {@link https://en.wikipedia.org/wiki/Cross-origin_resource_sharing}
 * {@link http://expressjs.com/en/4x/api.html#res.set}
 * @param {object} request the Request object
 * @param {object} response the Response object
 * @param {function} next function to continue execution
 * @returns {void}
 * @example
 * <code>
 * const express = require('express');
 * const corsHeaders = require('./middleware/cors-headers');
 *
 * const app = express();
 * app.use(corsHeaders);
 * </code>
 */
module.exports = (request, response, next) => {
    // http://expressjs.com/en/4x/api.html#res.set
    response.set({
        'Access-Control-Allow-Origin': '*',
        'Access-Control-Allow-Methods': 'DELETE,GET,PATCH,POST,PUT',
        'Access-Control-Allow-Headers': 'Content-Type,Authorization'
    });

    // intercept OPTIONS method
    if(request.method === 'OPTIONS') {
        response.send(200);
    } else {
        next();
    }
};