JavaScript Asynchronous and Flow-control

These examples demonstrate how to organize your asynchronous JavaScript code using the promises, reactive and flow-control patterns to avoid JavaScript callback hell.

JavaScript Callback Hell

fs.readFile(myDataFile, 'utf8', function(error, data) {
  if (error) throw error;
  fs.writeFile(myDataFile, data + ' callback 1', function(error) {
    if (error) throw error;
    fs.writeFile(myLogFile, data + ' callback 2', function(error) {
      if (error) throw error;
      console.log('Process has been finished!');
    });
  });
});

Examples

• ES6/2015 Promise constructor
• ES6/2015 Promise.all method
• ES6/2015 Promise.race method
• Async Module
• CO Module
• Async/Await
• Using async/await with Array.prototype.map()

References

• Comparing Callbacks, Promises and Async/Await in TypeScript
• How to use async/await to write better JavaScript
• Async/Await in JavaScript - What, Why and How - Fun Fun Function
• Promises Patterns
• Callback of heaven
• Callbacks vs Promises vs RxJs Observables vs async/await
• ES6 Promises
• Flow Control in Modern JS: Callbacks to Promises to Async/Await
• Hands-on with CO module
• kriskowal Q
• Learn about promises before you start using async/await
• Node Hero - Understanding Async Programming in Node.js
• Node.js Async Best Practice & Avoiding Callback Hell
• The async/await pitfalls

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In case you have doubt why I'm not using semicolon is because I got inspiration from these talks:

• Semicolons cannot save you!
• Are Semicolons Necessary in JavaScript?