Node variable scope

Question

So this seems like a basic thing but has caused extra work on my end this week several times. How do I define a variable within a function and make it available outside of said function.

var variables = { initial: 'To Start'};
var curl = require('curlrequest');


var options = {
   url: 'www.google.com',
   verbose: true,
   stderr: true
};

curl.request(options, function (err, data) {
   variables.testing123 = function() {return 'woking now';};
   variables.ting123 = 'I should be showing in console';
});

console.log(variables);

Console Output:

{ initial: 'To Start' }

The goal is to curl a url and store the returned json into a varialble to be used in another function to sort out highest resolution and build a download list from the available data. The latter part of the script is ready and but in order to dynamically do this I need to curl several urls and filter the json for each.

The problem is you're trying to work with an asynchronous function synchronously. — Mike Cluck, Aug 15 '16 at 22:29

score 0 · Accepted Answer · answered Aug 15 '16 at 22:37

The function you pass to curl.request is evaluated asynchronously, so anything you want to run after the request finishes needs to go into that function.

var curl = require('curlrequest');
var variables = { initial: 'To Start'};
var options = {
   url: 'www.google.com',
   verbose: true,
   stderr: true
};

curl.request(options, function (err, data) {
   variables.testing123 = function() {return 'woking now';};
   variables.ting123 = 'I should be showing in console';
   console.log(variables);
});

If you have a bunch of requests to process, you can use promises, or do something like this:

curl.request(options1, process);
curl.request(options2, process);
curl.request(options3, process);
var requestsProcessed = 0;
var results = [];
function process(err, data) {
    results.push(data);
    requestsProcessed++;
    if (requestsProcessed === 3) {
        // do something
    }
}

Node variable scope

1 Answers1