Express JS proxy to call web api - node.js

Question

I have the following code. And a web api which returns string array,
const express = require('express');
const proxy = require('express-http-proxy');
var app = express();
app.use('/proxy', proxy('http://localhost:56660/api/values'));
app.listen(3000);
When I tried to do localhost:3000/proxy I do not get a response,
But when I use app.use('/proxy', proxy('www.google.com')); , it redirects to google web site.
Please suggest me a best approach/solution:
I want to create a proxy server which gets url from browser (Application), modify the url, call the new url and send the response back to browser(Application).

Answer 1

You can get the URL to be proxied as a query parameter, modify it and then pass that URL to proxy, like this (use instead of app.use('/proxy', proxy('http://localhost:56660/api/values'));):
app.get('/proxy', (req, res, next) => {
const modifiedURL = modifyURL(req.query.url)
return proxy(modifiedURL)(req, res, next)
})
You can call you server with an URL like this (GET method):
https://my.server.com/proxy?url=https://urltobeproxied.com
UPDATE:
I think this would work according to your needs:
app.use('/proxy', (req, res, next) => {
const requestedUrl = `${req.protocol}://${req.get('Host')}${req.url}`
const modifiedURL = modifyURL(requestedUrl)
proxy(modifiedURL)(req, res, next)
})
UPDATE2:
app.use('/proxy', proxy('http://localhost:56660/api/values', {
proxyReqPathResolver: function(req) {
const requestedUrl = `${req.protocol}://${req.get('Host')}${req.url}`
const modifiedURL = modifyURL(requestedUrl)
return require('url').parse(modifiedURL).path;
}
}))
UPDATE3:
An example of proxy modifying the response (extracted from the package docs);
app.use('/proxy', proxy('http://localhost:56660/api/values', {
userResDecorator: function(proxyRes, proxyResData, userReq, userRes) {
data = JSON.parse(proxyResData.toString('utf8'));
data.newProperty = 'exciting data';
return JSON.stringify(data);
}
}))