node js async is not working

Question

When I try use async it is not defined:

async.whilst(func...);

Then I import it like so, but async is not a module it says:

var async = require('async');

So I then use npm to install it:

npm install async --save

But now when I run code I get error and I am not sure if I've installed the correct module:

.../node_modules/async/dist/async.js:4960
    iteratee(next);
    ^

TypeError: iteratee is not a function

Here is my full code...

var async = require('async');
async.whilst(gameloop);

function gameloop()
{
   // I will be adding code here to make it run at 30fps, and use deltatime.
   // This will be a gameloop for the multiplayer game I am creating.
   console.log('yipee!');
   return true;
}

I noticed that yipee! is being logged once and then the error happened.

Has anyone got an idea on how to fix this one?

Thanks in advance,

David.

Edit: Using @nico answer, I got working code: http://pastebin.com/ZCFstqsa

async.whilst expects two arguments. You are only passing one. The documentation is pretty clear: "Repeatedly call iteratee, while test returns true. Calls callback when stopped, or an error occurs." — Felix Kling
– Felix Kling, Commented Jan 5, 2017 at 17:57

nico · Accepted Answer · 2017-01-05 17:57:20Z

3

That's because you're missing the second argument called iteratee
http://caolan.github.io/async/docs.html#whilst
You should do something like this instead
async.whilst(function allways() { return true; }, gameloop);

answered Jan 5, 2017 at 17:57

nico

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5 Comments

David Callanan Over a year ago

Thanks for the help. The error is now gone, but the function gameloop only gets called once. Do you know why this might be happening?

nico Over a year ago

That's because you need to call a callback when the execution finishes. The gameloop should look like this: function gameloop(cb) { console.log("yipee!"); cb();}

David Callanan Over a year ago

Thanks, I got the loop working. But there is a RangeError: Maximum call stack size exceeded. Is there a way to make it go on forever? Here is my updated code: pastebin.com/FAWjvQR8. It only execute for 9ms.

nico Over a year ago

If you're running under a node.js environment you can call this instead of calling next directly: process.nextTick(next);

David Callanan Over a year ago

Just after figuring it out too. Thanks a million :)

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