Access variable outside scope? nodejs

Question

function art(dataToArt){
  var figlet = require('figlet');
var result;
figlet(dataToArt, function(err, data) {
    if (err) {
        console.log('Something went wrong...');
        console.dir(err);
        return;
    }
    var result = data;
});
return result;
}

test = art('Hello World');

console.log(test);

Running this gives "undefined". How to access the changes made by function figlet to the variable result defined outside the function figlet.

It seems like figlet is an asynchronous function. You can't. You need to do all your work inside the callback. — Explosion Pills
– Explosion Pills, Commented Mar 6, 2016 at 17:07
I'm using npmjs.com/package/figlet and I've never ever used nodejs — Garvit Jain
– Garvit Jain, Commented Mar 6, 2016 at 17:08
"Why is my variable unaltered after I modify it inside of a function?" Though, you are declaring result in multiple scopes, so you're returning a different result than you're assigning data to. However, changing that (result = data; without var) won't fix the issue of execution timing. — Jonathan Lonowski
– Jonathan Lonowski, Commented Mar 6, 2016 at 17:08
Just look at the "simple example" in the figlet doc where to use the result data of your asynchronous callback function. — crackmigg
– crackmigg, Commented Mar 6, 2016 at 17:11

num8er · Accepted Answer · 2016-03-06 17:24:58Z

9

It's asynchronous code. It cannot do return. It must have callback and respond after job done.

var figlet = require('figlet');

function art(dataToArt, callback)
{ 
    figlet(dataToArt, function(err, data) { 
        if (err) { 
            console.log('Something went wrong...'); 
            console.dir(err); 
            return callback(''); 
        } 

        callback(data);
    }); 
} 


art('Hello World', function (data){
    console.log(data);
    // also You can do operations here.
    // for example can save to db or send to somewhere.
});

answered Mar 6, 2016 at 17:24

num8er

19.5k4 gold badges50 silver badges61 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Community · Accepted Answer · 2017-05-23 12:17:32Z

5

The answer by @num8er is perfectly correct.

I personally like using promises:

var figlet = require('figlet');

function art(dataToArt) {
    return new Promise(function(fullfil, reject) {
        figlet(dataToArt, function(err, data) {
            if (err) {
                reject(err);
            } else {
                fullfil(data);
            }
        });
    });
}

art('Hello World').then(function(result) {
    console.log(result);
});

edited May 23, 2017 at 12:17

CommunityBot

11 silver badge

answered Mar 6, 2016 at 19:25

Perspectivus

9901 gold badge9 silver badges24 bronze badges

1 Comment

Garvit Jain Over a year ago

This worked locally but not in my Telegram Bot Anyways thanks for the Answer, sorry I cannot +1 your answer because stackoverflow isn't letting me.

Collectives™ on Stack Overflow

Access variable outside scope? nodejs

2 Answers 2

Comments

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related