What's New in JavaScript

This talk was given at JSSummit 2013. Entitled "Avoiding Callback Hell with Async.js", my talk focused on common pitfalls with asynchronous functions and callbacks in JavaScript, and using the async.js library and its advanced control flows to create cleaner, more manageable code.

Držte si klobouky, protože se proletíme letem světem – asynchronně, od PHP, přes Javascript, Web, C# až po Kotlin.

This document discusses using promises in Node.js to avoid callback hell. It explains that Node.js is event-based and non-blocking, allowing it to handle multiple requests simultaneously. However, nested callbacks can result in unwieldy callback pyramids or "callback hell". Promises provide a way to write asynchronous code in a more linear way using method chaining. Key benefits include separation of concerns between wrapping asynchronous functions and controlling flow, as well as more readable code. The document provides examples of chaining, nesting, combining, and creating promises using deferred objects in the Q promise library.

This document discusses the benefits of using Redux-Observable over Redux-Thunk for handling asynchronous logic in Redux applications. It begins by showing an example of how a search functionality would be implemented using Redux-Thunk, which requires additional logic for canceling requests. It then demonstrates how the same search functionality can be implemented more concisely and readably using Redux-Observable through the use of Epics. Overall, the document argues that Redux-Observable provides a simpler and more efficient way to solve common asynchronous problems compared to Redux-Thunk.

- JavaScript has come a long way from its early days of form validation and image rollovers in 1995 to modern innovations like ES2015, Promises, async/await, and Web Assembly. - Today, JavaScript features like classes, arrow functions, and template strings in ES2015 are widely adopted, and new standards like Promises, generators, and async programming have revolutionized asynchronous JavaScript. - Emerging web platform technologies like Web Components, Service Workers, and CSS Paint enable new kinds of custom elements, offline/progressive web apps, and painting APIs, while proposals like decorators, value types, and module loading continue pushing the language forward.

This document discusses using RxJS (Reactive Extensions for JavaScript) to add interactivity and animation to an autocomplete search widget. Key events are turned into observables and used to make AJAX requests and trigger animations. Observables are merged, concatenated, and flattened to coordinate the asynchronous events and animations over time. Functional programming concepts like map, filter, and reduce are used to transform and combine the observable streams.

This document discusses asynchronous programming and avoiding race conditions. It covers how asynchronous actions allow the main program flow to continue processing without blocking on I/O. It also discusses how asynchronous programming works with callbacks and promises rather than sequential execution. It provides examples of using libraries like Async to control asynchronous flows and common pitfalls to avoid like double callbacks and unexpected asynchronous behavior.

Promise patterns provide an asynchronous programming model for JavaScript using promises. Promises allow separating business logic from asynchronous API providers by defining a standard asynchronous API. Common patterns are callbacks, events, and promises. Promises improve on callbacks and events by allowing parallel asynchronous operations, error handling, and progress tracking in a standardized way.

Reactive programming models asynchronous data streams as signals that produce events over time. ReactiveCocoa is a framework that implements reactive programming in Objective-C. It uses signals to represent asynchronous data streams and operators to transform and combine signals. ReactiveCocoa code separates the logic to produce and consume data, making it more modular, reusable, testable and by reducing state and mutability. While the syntax is different, learning to think reactively can improve code quality and stability.

This document discusses JavaScript promises and asynchronous programming. It covers how promises represent asynchronous operations as objects, how to chain promises together using .then(), and how promises can be created using the closure or deferred syntax. It also discusses promise terminology, states, error handling, and common promise patterns and use cases. High-order functions and promise utility functions provided by promise libraries are presented. Guidelines for testing promises are also included.

The document provides information about Swift Core, which includes the core libraries and functionality of the Swift programming language. It lists some of the key Swift libraries like swiftAST and swiftLLVMParses. It also describes the documentation build process and lists important files that define the language like Attr.def, Builtin.def, and MappedTypes.def. The document outlines how to install and develop Swift in Xcode and highlights some core language functions.

This document discusses JavaScript promises as an abstraction pattern for handling asynchronous code. It explains why promises are useful by describing some of the issues with callback-based asynchronous code, such as callback hell and lack of readability. The document then provides examples of how to create and use promises to handle sequential and parallel asynchronous tasks in a more maintainable way using chaining and batching. It also discusses how promises are supported in browsers, Node.js, and common promise libraries like Q, RSVP, when.js, and Bluebird.

This document discusses callbacks, promises, and generators for handling asynchronous code in JavaScript. It begins by explaining callbacks and the issues they can cause like "callback hell". It then introduces promises as an alternative using libraries like Q that allow chaining asynchronous operations together. Generators are also covered as a way to write asynchronous code that looks synchronous when combined with promises through libraries like CO. Overall, it recommends using an asynchronous pattern supported by a library to manage complex asynchronous code.

This document discusses using the Kinect sensor with Node.js. It describes connecting the Kinect to Node.js using the Audio Data API and Socket.IO for real-time data streaming. Code examples are provided for an Express server to handle requests and websockets, and using TCP/IP to receive Kinect sensor data and broadcast it over websockets.

Promises provide a consistent way to write asynchronous code in JavaScript by abstracting callbacks into objects. Some key benefits of promises include: handling errors through rejection instead of nested callbacks, ability to chain operations together through promise methods like .then(), and restoring synchronous-like control flow. The document discusses how promises improve on traditional callback-based patterns and provides examples of converting common asynchronous patterns to use promises.

This presentation covers from the basics of what is an async task and how it works to more advanced features of Celery.

node.js is an evented server-side Javascript framework powered by the Google V8 Javascript engine. It is a platform ideal for creating highly scalable web applications. It has the same simplicity of frameworks such as Sinatra, but is designed to be more peformant from the ground up. This performance is achieved by making all network I/O non blocking and all file I/O asynchronous. We will go over how that impacts the development experience, and walk through a simple web application. Javascript is foundational to this type of I/O because it is already evented by design. We will also take a brief look a similar evented frameworks such as ruby`s EventMachine.

This document summarizes a JavaScript training by Rick Beerendonk. It covers ECMAScript versions from 2015 to 2017, as well as React and Redux. The training includes components, properties, state, events, actions, reducers and stores. Sample code and slides are available on GitHub. Contact information is provided to sign up for the training.

He will start you at the beginning and cover prerequisites; setting up your development environment first. Afterward, you will use npm to install react-native-cli. The CLI is our go to tool. We use it to create and deploy our app. Next, you will explore the code. React Native will look familiar to all React developers since it is React. The main difference between React on the browser and a mobile device is the lack of a DOM. We take a look a many of the different UI components that are available. With React Native you have access to all of the devices hardware features like cameras, GPS, fingerprint reader and more. So we'll show some JavaScript code samples demonstrating it. We will wrap up the evening by deploying our app to both iOS and Android devices and with tips on getting ready for both devices stores.

This document provides an overview of an ES6 hackathon focusing on new features in ES6 including block scope, modules, destructuring, arrow functions, classes, template literals, internationalization, spread syntax, generators, sets, promises and more. Attendees will have 30 minutes to work on code challenges exploring these new ES6 features using resources like JSFiddle and TypeScript. The challenges involve updating functions to use new syntax like arrow functions, default parameters and object shorthand, satisfying class assertions, and improving outputs using template strings and internationalization.

JavaScript keeps on expanding. As adoption of the extensive new features from ES6 has spread and projects have adapted, the language has continued to evolve under the guidance of Ecma TC39. Over the past two years, another handful of constructs entered the ECMAScript specification. And there are nearly two dozen more proposals on the cusp of being added. One thing is certain: the JavaScript community is not slowing down! How can we determine when it is “safe” to use a new feature? Investigate the new and proposed language features of JavaScript. Understand the TC39 review process. And most of all, become empowered to prepare for what lies ahead.