Why data isn't being added to array in NodeJS

Question

What is wrong with my code:

var emailExistence = require('email-existence');

var emails = ['[email protected]', '[email protected]'];
var validEmails = [];


emails.forEach(function(email) {
    emailExistence.check(email, function(err, res) {
        if(res == true) {
            validEmails.push(email); //No email is being added
            console.log(email); //Emails are written to the console
        }
    });
});

validEmails.forEach(function(email) {
    console.log(email); //Nothing is written to the console
});

The validEmails array isn't being populated.

possible duplicate of How to return the response from an asynchronous call? — thefourtheye
– thefourtheye, Commented Apr 13, 2015 at 7:10
In addition to wrong way of checking results of asynchronous method there is very good possibility that gmail and other open servers will simply refuse to provide information need for "email-existence" to detect valid e-mail addresses. — Alexei Levenkov
– Alexei Levenkov, Commented Apr 13, 2015 at 7:14
@AlexeiLevenkov I did some testing, and this script returns true when passing valid emails, but I believe that some servers will refuse to provide this information. — Klevis Miho
– Klevis Miho, Commented Apr 13, 2015 at 7:17
@thefourtheye I just want to know why the array validEmails doesn't fill with data using validEmails.push(email). — Klevis Miho
– Klevis Miho, Commented Apr 13, 2015 at 7:19
@KlevisMiho Trust me, its worth spending a day on it. Its a must read for all of us :-) — thefourtheye
– thefourtheye, Commented Apr 13, 2015 at 7:33

sachin.ph · Accepted Answer · 2015-04-13 11:28:07Z

1

It is because

validEmails.forEach(function(email) {
console.log(email); //printed at last
});

is outside the callback.So it executed before executing the callback.You will have to use validEmails after every thing has been added or all callback completed.

You can use underscore's after for these kind of things.

you can try with

var _U = require('underscore');
var afterAllEmailChecks = _U.after(emails.length,function(){
    validEmails.forEach(function(email) {
        console.log(email); //Nothing is written to the console
    });
});
emails.forEach(function(email) {
    emailExistence.check(email, function(err, res) {
        if(res == true) {
            validEmails.push(email); //No email is being added
            console.log(email); //Emails are written to the console
        }
       afterAllEmailChecks();
    });
});

edited Apr 13, 2015 at 11:28

answered Apr 13, 2015 at 7:20

sachin.ph

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2 Comments

Klevis Miho Over a year ago

is it possible for you to edit my function so the logic works? As I am still having trouble on how to do that.

sachin.ph Over a year ago

modified my answer.Try it.

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