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As part of a program I am writing, I'd like to have a helper function that shortens some long URLs that are created. I found this package: and am attempting to change the code so that it simply stores the string in a variable and returns it. I am having some issues with scope. the variable resData is never actually updated and return is always an empty string. How can I get this returned string into the global variable and return it? Thanks

var http = require("http")

module.exports = {
    shorten: function(url) {

        var resData = ''

        http.get('[tinyurl api endpoint]' + encodeURIComponent(url), (res) => {
            res.setEncoding('utf8')
            res.on('data', (chunk) => {resData += chunk})
            res.on('end', () => {
                resData = resData.toString()
                //this contains the link, and can be console.logged
            })
        }).on('error', (e) => {
            console.log(e)
        })

        return resData //returns empty string
}
};
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2 Answers 2

Reset to default
1

do this 

    var http = require("http")

    module.exports = {
        shorten: function(url,cb) {

            var resData = ''

            http.get('[tinyurl api endpoint]' + encodeURIComponent(url), (res) => {
                res.setEncoding('utf8')
                res.on('data', (chunk) => {resData += chunk})
                res.on('end', () => {
                    resData = resData.toString()
                    //this contains the link, and can be console.logged
                    cb(null,resData)  //<----- use callback (thanks robertklep)
                })
            }).on('error', (e) => {
                console.log(e)
            })

           //--> return resData //returns empty string as node is non-blocking io, this line will be executed before http response is received
      }
    };

//index.js

var http = require('./path/to/that/module')
http.shorten(url,function(error,result){ console.log(result) })
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4 Comments

@robertklep I didnt get you... will that code not work? if not why?
You could always try running the code you're suggesting as an answer.
Much better, although the Node.js convention for callbacks is that the first argument always represents an error. So you should do this: cb(null, resData) (and in the call: function(err, result) { ... }).
Yes, it's working, but it doesn't follow convention, which may confuse people, or cause problems later on.
1

Try to use with callback function 

shorten: function(url,callback) {

    var resData = ''

    http.get('[tinyurl api endpoint]' + encodeURIComponent(url), (res) => {
        res.setEncoding('utf8')
        res.on('data', (chunk) => {resData += chunk})
        res.on('end', () => {
            resData = resData.toString()
            //this contains the link, and can be console.logged
            callback(null,resData); //<----here
        })
    }).on('error', (e) => {
        console.error(e);
        callback(e,null); //<----- and here
    })
}
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