How to return a value from a nested API function

Question

I have a function called wikiCount that I'm using to wrap another function from an API like this:

 var wikiCount = function(wikiPage, word){

      wtf_wikipedia.from_api("Toronto", "en", function(markup){

        var obj = wtf_wikipedia.plaintext(markup)
        var a = obj.toLowerCase().split(" ").count(word)
        return a

    })
}

How can I return a value from the nested API function so that I can use it in the wrapper function. The whole purpose of doing this is because I'm trying to access the variable "a" outside the function.

What is the API? They probably have documentation or example code that would help with this. — 4castle, May 09 '16 at 21:18
There are answers to this question here: [How do I return the response from an asynchronous call?](http://stackoverflow.com/questions/14220321/how-do-i-return-the-response-from-an-asynchronous-call) — 4castle, May 09 '16 at 21:22

score 0 · Answer 1 · answered May 09 '16 at 21:06

A cool way is with promises:

var Promise = require('bluebird');

function wikiCount(wikiPage, word){

     return new Promise(function(resolve, reject) {

        wtf_wikipedia.from_api("Toronto", "en", function(markup){

            var obj = wtf_wikipedia.plaintext(markup)
            var a = obj.toLowerCase().split(" ").count(word)

            resolve(a);

        });
    });
}

wikiCount('somePage', 'someWord')
.then(function(result) {
  // do something with the result
  // this is 'a' that you resolved in the function above
});

The above example uses the bluebird promise library. If you're in a browser or a Node.js runtime that supports ES6, you can use native Promises.

The above is referred to as "Promisification":

Promisification means converting an existing promise-unaware API to a promise-returning API.

How to return a value from a nested API function

1 Answers1