co wrapper as Task.jsm API
Last updated 4 years ago by jsantell .
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$ cnpm install co-task 
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co-task Build Status

co wrapper as Task.jsm API. Task.jsm is a subset of task.js for use inside Mozilla.


co-task requires harmony generators and native Promise, so running node >= 0.11.2 is required with the --harmony flag.

Install via npm

$ npm install co-task --save

And running with --harmony flags in node, say file.js consumes co-task, run via:

$ node --harmony file.js



The "Task.spawn" function takes a generator function and starts running it as a task. Every time the task yields a promise, it waits until the promise is fulfilled. "Task.spawn" returns a promise that is resolved when the task completes successfully, or is rejected if an exception occurs.

function fetchUserData (user) {
  return Task.spawn(function* () {
    var user = yield getUser();
    return yield getDataForUser(user);

fetchUserData("big foot").then(function (data) {


Create and return an 'async function' that starts a new task. This is similar to 'spawn' except that it doesn't immediately start the task, it binds the task to the async function's 'this' object and arguments, and it requires the task to be a function. It simplifies the common pattern of implementing a method via a task, like this simple object with a 'greet' method that has a 'name' parameter and spawns a task to send a greeting and return its reply.

let greeter = {
  message: "Hello, NAME!",
  greet: Task.async(function* (name) {
    return yield sendGreeting(this.message.replace(/NAME/, name));


npm test


MIT License, Copyright (c) 2014 Jordan Santell

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  • co ^3.1.0
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