CODEWITHSUNDEEP
javascriptnode.jsexpress
Akshay
Akshay

Reputation: 161

Getting response object to browser

Hi I have a function in router.js in NODEJS :

const authenticateUser = (req, res, next) => {
  //something
};

When my application is running this function gets called. I need to inspect the response object. Is there any way that I can print my response object to client side i.e. browser or print in proper format of JSON which shows internal objects as well.

Upvotes: 1

Views: 1032

Answers (2)

asdru
asdru

Reputation: 1264

I think that one way to log server message to the user browser console could be printing a script tag and in that <script> you have to console.log (or console.error) your server message

const authenticateUser = (req, res, next) => {
  // ...
  res.write(`<script>console.log('server log:', ${JSON.stringify(your_object)})</script>`)
  // ...
  // res.end();
};

Of course you can enclose the logging part in a function or a template literal or, even better, a class with a template literal method

ie

// any-file.mjs

// log messages to the browser console
class BrowserLogger {
    constructor({method = "log", ...tail}) {
        Object.assign(this, {method, ...tail})
    }

    // template literal
    print(strings, ...args) {
        // joins arguments
        var all = strings.flatMap( (s, i) => [s, args[i]])
        // print on the browser console
        return `<script>console.${this.method}(${
            all.map(this.handler.bind(this))
        })</script>`
    }

    handler(current){
        return JSON.stringify(current)
    }
}

// crete a few instances of the BrowserLogger class
// one for generic messages
const logger = new BrowserLogger({})
// one for errors
const errorLogger = new BrowserLogger({
    method: "error",
    // custom handler for errors :)
    handler(e){
        return this.constructor.prototype.handler(e instanceof Error ? e.stack : e)
    }
})

var obj = {foo:"bar"}

const authenticateUser = (req, res, next) => {

    // ...

    // generic messages
    res.write(logger.print `obj:${obj}, msg:${{ foobar: true }}`)
    // error
    res.write(errorLogger.print `${
        new Error("error message from the server!")
    }`)

    // ...

    res.end();
};

// use authenticateUser in a server
import http from "http"
var port = 8080
var server = http.createServer(authenticateUser)
server.listen(port);

Upvotes: 0

Sagar Jajoriya
Sagar Jajoriya

Reputation: 2375

Use res.send(your_object). It will send the response to the browser.

Upvotes: 1

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