async/await replace in Nodejs

Question

I am trying to do a function like async/await in C# but in node js I have found an example but It gives me an error.

here is the code

function* gotNews(response){    
        console.log("in gotNews");
        str='';
        response.on('data', function (chunk) {
            str += chunk;
        });    
        response.on('end', function () {
              str = JSON.parse(str);
              console.log(str);
              fetchCategories();
        });
        return str;
}


function fetchNews(sourceURL){
        console.log("in fetch news");
             sourceURL = url.parse(sourceURL);
             console.log(sourceURL);
        var options = 
        {
            host: sourceURL.host,
            port: 134,
            path: sourceURL.path,

            method: 'GET',
        };
        var req = http.request(options,yield gotNews);//start request and recive response in gotSources
        req.end();
}

I am using the * yield operation but gives me an error

ErrorC:\Users\Alaa\Desktop\Fluid_layout_with_jQuery_Masonry\1\app.js:198
        var elnewselygat = yield gotNews();
                                 ^^^^^^^
SyntaxError: Unexpected identifier
    at Module._compile (module.js:439:25)
    at Object.Module._extensions..js (module.js:474:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)
    at Function.Module.runMain (module.js:497:10)
    at startup (node.js:119:16)
    at node.js:901:3

is it something special with function* (I mean STAR)? I never saw function declared like that — tomekK
– tomekK, Commented Nov 20, 2013 at 11:44
@tomekK The * in function* is your async keyword. yield is your await keyword. — Mohamed Naguib
– Mohamed Naguib, Commented Nov 20, 2013 at 11:45
As I said there is no such a thing native in JavaScript. The example which you show requires a custom library github.com/bjouhier/galaxy and I guess that it reads your functions and does some magic to remove the * sign. — Krasimir
– Krasimir, Commented Nov 20, 2013 at 11:53
Have you tried promises? github.com/cujojs/when I know its not the same, but as far as I know, it helps you solve the same issue in a different way — Hernan Rajchert
– Hernan Rajchert, Commented Nov 20, 2013 at 11:57
Did you run node with the --harmony parameter? You'll also need node >= 0.11.2. — Paul Mougel
– Paul Mougel, Commented Nov 20, 2013 at 12:03

Stephen Cleary · Accepted Answer · 2013-11-20 12:33:57Z

2

You'll need generators and promises to make it as easy as async/await/Task.

As @Paul stated, generators are a "future feature" so you need to pass --harmony or --harmony-generators. Also, generators are supported in V8 3.19, which is only in Node.js 0.11.2 or newer.

The JavaScript community is currently considering a number of possible approaches; there's a good overview of several of them here, and there are other libraries out there as well.

answered Nov 20, 2013 at 12:33

Stephen Cleary

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Lucio M. Tato · Accepted Answer · 2013-12-04 16:13:52Z

0

check: https://github.com/luciotato/waitfor-es6

It does what you want, with generators. (no promises required)

function* ----> c# async

yield wait.for(fn...) ---> c# await

answered Dec 4, 2013 at 16:13

Lucio M. Tato

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Jason Livesay · Accepted Answer · 2015-07-26 19:12:00Z

0

You can use async/await with babel --stage 1 --optional runtime.

answered Jul 26, 2015 at 19:12

Jason Livesay

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