This document provides an overview of various JavaScript concepts and techniques, including:
- Prototypal inheritance allows objects in JavaScript to inherit properties from other objects. Functions can act as objects and have a prototype property for inheritance.
- Asynchronous code execution in JavaScript is event-driven. Callbacks are assigned as event handlers to execute code when an event occurs.
- Scope and closures - variables are scoped to functions. Functions create closures where they have access to variables declared in their parent functions.
- Optimization techniques like event delegation and requestAnimationFrame can improve performance of event handlers and animations.
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.
One of the main strengths of serverless and AWS Lambda is that, from a developer perspective, your focus is mostly shifted toward implementing business logic. Anyway, when you are writing an handler, you still have to deal with some common technical concerns outside business logic, like input parsing and validation, output serialization, error handling, etc. Very often, all this necessary code ends up polluting the pure business logic code in your handlers, making the code harder to read and to maintain. In other contexts, like generic web frameworks (express, fastify, hapi, etc.), this problem has been solved using the middleware pattern. Middy brings the middleware pattern into AWS Lambda making it easier to focus on business logic and reuse the boilerplate code across different functions.
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.
One of the main strengths of serverless and AWS Lambda is that, from a developer perspective, your focus is mostly shifted toward implementing business logic. Anyway, when you are writing an handler, you still have to deal with some common technical concerns outside business logic, like input parsing and validation, output serialization, error handling, etc. Very often, all this necessary code ends up polluting the pure business logic code in your handlers, making the code harder to read and to maintain. In other contexts, like generic web frameworks (express, fastify, hapi, etc.), this problem has been solved using the middleware pattern. Middy brings the middleware pattern into AWS Lambda making it easier to focus on business logic and reuse the boilerplate code across different functions.
Understanding reactive programming with microsoft reactive extensionsOleksandr Zhevzhyk
We all want our applications to be responsible, reliable and testable. But event-driven paradigm sometimes could lead us to obscured or, even worse, messy code. Let’s look into the world, where generated data, background tasks and events are stuck together as asynchronous data streams to achieve a better result.
Introduction to reactive programming & ReactiveCocoaFlorent Pillet
A short introduction to the concepts of functional reactive programming, and their implementation in ReactiveCocoa, a framework for iOS and OS X developers.
This speech was given at CocoaHeads Paris, October 9th 2014
Games Development with Drools. Covers text adventure games, pong, wumpus and invaders. As well as a general rules introduction
Those games were also covered separately in other videos
Invaders : http://tinyurl.com/jwml42m
Wumpus : http://tinyurl.com/na376bu
Pong : http://tinyurl.com/pkgub9b
Text Adventure : http://tinyurl.com/mfggm8n
Ajax is the web's hottest user interface. Struts is Java's most popular web framework. What happens when we put Ajax on Struts?
In this session, we look at writing a new Struts 2 application from square one, using the Yahoo User Interface (YUI) Library on the front end, and Struts 2 on the backend. YUI provides the glitz and the glamour, and Struts 2 provides the dreary business logic, input validation, and text formatting.
During the session, we will cover
* How to integrate an Ajax UI with Struts 2
* Basics of the Yahoo User Interface (YUI) Library
* Business services Struts can provide to an Ajax UI
Who should attend: Ajax developers who would like to utilize Struts as a back-end, and Struts developers who would like to utilize Ajax as a front-end.
To get the most from this session, some familiarity with an Ajax library, like YUI or Dojo, is helpful.
Understanding reactive programming with microsoft reactive extensionsOleksandr Zhevzhyk
We all want our applications to be responsible, reliable and testable. But event-driven paradigm sometimes could lead us to obscured or, even worse, messy code. Let’s look into the world, where generated data, background tasks and events are stuck together as asynchronous data streams to achieve a better result.
Introduction to reactive programming & ReactiveCocoaFlorent Pillet
A short introduction to the concepts of functional reactive programming, and their implementation in ReactiveCocoa, a framework for iOS and OS X developers.
This speech was given at CocoaHeads Paris, October 9th 2014
Games Development with Drools. Covers text adventure games, pong, wumpus and invaders. As well as a general rules introduction
Those games were also covered separately in other videos
Invaders : http://tinyurl.com/jwml42m
Wumpus : http://tinyurl.com/na376bu
Pong : http://tinyurl.com/pkgub9b
Text Adventure : http://tinyurl.com/mfggm8n
Ajax is the web's hottest user interface. Struts is Java's most popular web framework. What happens when we put Ajax on Struts?
In this session, we look at writing a new Struts 2 application from square one, using the Yahoo User Interface (YUI) Library on the front end, and Struts 2 on the backend. YUI provides the glitz and the glamour, and Struts 2 provides the dreary business logic, input validation, and text formatting.
During the session, we will cover
* How to integrate an Ajax UI with Struts 2
* Basics of the Yahoo User Interface (YUI) Library
* Business services Struts can provide to an Ajax UI
Who should attend: Ajax developers who would like to utilize Struts as a back-end, and Struts developers who would like to utilize Ajax as a front-end.
To get the most from this session, some familiarity with an Ajax library, like YUI or Dojo, is helpful.
Every bit of JavaScript code runs inside an Execution Context. This key principle is the base of the closures. Mastering closures is key when writing JS code and apps.
Given for Easy7 SIGCHI-SI in Bangalore 1/5/2007
With the advent of Ajax, new patterns of interaction have emerged on the Web. Bill Scott provides insight on how to best take advantage of the power of Ajax technology for designing a great user experience through a series of best practices, summarized as eight key principles. Each principle and its nuances are illustrated in detail with real world examples and counter-examples from both inside and outside Yahoo!
Introduction to programming with Ajax. Covers XMLHttpRequest, XML, JSON, JavaScript, HTML, CSS, Dom Scripting, Event Handling with some examples from YUI library. I gave this talk a dozen or more times in workshops throughout the U.S. & in Amsterdam (AdaptivePath, Yahoo!, Federal Reserve, Ultimate Software, VeriSign, United Online, etc.) . Jan 2006 - Feb 2007.
JavaScript Multithread or Single Thread.pptxRAHITNATH
The most functional yet intricately constructed programming language is JavaScript. Understanding how the syntax is used in engines, such as V8 engines for chromium, is challenging. We are successfully completing tasks in Chrome at the same time. This PPT will assist you in learning about the most crucial aspects and use of JavaScript, which will help you comprehend when and where the language is required. Java provides a superior platform by using multi-threading ways to optimize the process, but how can JavaScript manage to achieve the same thing even in a better way to compile and provide us a real-time user interface on webpages even after a significant amount of time has passed.
JavaScript's non-blocking approaches offer a better method of process resolution and execution with regard to load and priority to improve user experience. Even better are the non-blocking approaches and some browser architecture. The topic focuses on JavaScript's end-to-end workflow in Chrome's V8 engine and how it distributes its load and processes with the aid of queues made available by Chrome's architectural design.
Object-Oriented JavaScript presentation given at the 2010 ESRI Developer Summit. Code and slides are also available at http://github.com/kvangork/OOJS-Presentation
Find me on twitter @kvangork
or my blog http://prng.vangorkom.org
Object-Oriented JavaScript presentation given at ESRI's 2010 Developer Summit. Slides and code available at http://github.com/kvangork/OOJS-Presentation
Find me on twitter @kvangork
or at my blog: http://prng.vangorkom.org
JavaScript Advanced - Useful methods to power up your codeLaurence Svekis ✔
Get this Course
https://www.udemy.com/javascript-course-plus/?couponCode=SLIDESHARE
Useful methods and JavaScript code snippets power up your code and make even more happen with it.
This course is perfect for anyone who has fundamental JavaScript experience and wants to move to the next level. Use and apply more advanced code, and do more with JavaScript.
Everything you need to learn more about JavaScript
Source code is included
60+ page Downloadable PDF guide with resources and code snippets
3 Challenges to get you coding try the code
demonstrating useful JavaScript methods that can power up your code and make even more happen with it.
Course lessons will cover
JavaScript Number Methods
JavaScript String Methods
JavaScript Math - including math random
DOMContentLoaded - DOM ready when the document has loaded.
JavaScript Date - Date methods and how to get set and use date.
JavaScript parse and stringify - strings to objects back to strings
JavaScript LocalStorage - store variables in the user browser
JavaScript getBoundingClientRect() - get the dimensions of an element
JavaScript Timers setTimeout() setInterval() requestAnimationFrame() - Run code when you want too
encodeURIComponent - encoding made easy
Regex - so powerful use it to get values from your string
prototype - extend JavaScript objects with customized powers
Try and catch - perfect for error and testing
Fetch xHR requests - bring content in from servers
and more
No libraries, no shortcuts just learning JavaScript making it DYNAMIC and INTERACTIVE web application.
Step by step learning with all steps included.
Not so long ago Microsoft announced a new language trageting on front-end developers. Everybody's reaction was like: Why?!! Is it just Microsoft darting back to Google?!
So, why a new language? JavaScript has its bad parts. Mostly you can avoid them or workaraund. You can emulate class-based OOP style, modules, scoping and even run-time typing. But that is doomed to be clumsy. That's not in the language design. Google has pointed out these flaws, provided a new language and failed. Will the story of TypeScript be any different?
A brief look at the new features coming in Javascript ES6:
- Scope and control
- Iterators and Generators
- Collections
- Typed objects
- Direct proxies
- Template strings
- API improvements
- Modularity
Think Async: Asynchronous Patterns in NodeJSAdam L Barrett
JavaScript is single threaded, so understanding the async patterns available in the language is critical to creating maintainable NodeJS applications with good performance. In order to master “thinking in async”, we’ll explore the async patterns available in node and JavaScript including standard callbacks, promises, thunks/tasks, the new async/await, the upcoming asynchronous iteration features, streams, CSP and ES Observables.
The Return of JavaScript: 3 Open-Source Projects that are driving JavaScript'...Ben Teese
Web development is experiencing a major change at the moment. Users are demanding increasingly responsive and interactive web applications. The mobile web has taken off. And closed platforms like Flash are yielding to open standards like HTML 5.
In this presentation I’ll argue that the language that will underpin this revolution is JavaScript – despite it’s poor reputation. Furthermore, I’ll explain how JavaScript’s resurrection is being driven by a slew of new open-source technologies.
For video of this presentation, see http://www.youtube.com/watch?v=SiCD3Nbf810
The next version of JavaScript, ES6, is starting to arrive. Many of its features are simple enhancements to the language we already have: things like arrow functions, class syntax, and destructuring. But other features will change the way we program JavaScript, fundamentally expanding the capabilities of the language and reshaping our future codebases. In this talk we'll focus on two of these, discovering the the myriad possibilities of generators and the many tricks you can pull of with template strings.
Workshop JavaScript Testing. Frameworks. Client vs Server Testing. Jasmine. Chai. Nock. Sinon. Spec Runners: Karma. TDD. Code coverage. Building a testable JS app.
Presentado por ing: Raúl Delgado y Mario García
Sample JavaScript Code Laurence Svekis
JavaScript Closure
A closure in JavaScript is a function that has access to the variables in its parent scope, even after the parent function has completed execution. This allows for data to be “closed over” or remembered by the inner function, even after the outer function has returned.
Here, the makeCounter function returns an inner function that has access to the count variable declared in its parent scope, and can “remember” the current count value even after the makeCounter function has completed execution. Each time the inner function is called, it returns the current value of count and increments it by 1.
JavaScript Closure Advanced
In this example, the makeAdder function takes in a single argument x and returns an inner function that takes in a second argument y. The inner function has access to the x variable declared in the parent scope and uses it to add x and y together and return the result.
We can see here that the outer function makeAdder has been executed twice and it returns two different inner functions which are assigned to different variables add5 and add10 and these inner functions are able to remember their respective parent scope values of x.
(SKIP TO SLIDE 113 IF YOU ALREADY KNOW WHAT TWITTER IS.) A presentation I gave at the Nurun Montreal head office in February 2009. The subject covers an idea I had about leveraging the viral potential of Twitter to benefit both its users and third parties looking for some marketing love.
Understanding User Behavior with Google Analytics.pdfSEO Article Boost
Unlocking the full potential of Google Analytics is crucial for understanding and optimizing your website’s performance. This guide dives deep into the essential aspects of Google Analytics, from analyzing traffic sources to understanding user demographics and tracking user engagement.
Traffic Sources Analysis:
Discover where your website traffic originates. By examining the Acquisition section, you can identify whether visitors come from organic search, paid campaigns, direct visits, social media, or referral links. This knowledge helps in refining marketing strategies and optimizing resource allocation.
User Demographics Insights:
Gain a comprehensive view of your audience by exploring demographic data in the Audience section. Understand age, gender, and interests to tailor your marketing strategies effectively. Leverage this information to create personalized content and improve user engagement and conversion rates.
Tracking User Engagement:
Learn how to measure user interaction with your site through key metrics like bounce rate, average session duration, and pages per session. Enhance user experience by analyzing engagement metrics and implementing strategies to keep visitors engaged.
Conversion Rate Optimization:
Understand the importance of conversion rates and how to track them using Google Analytics. Set up Goals, analyze conversion funnels, segment your audience, and employ A/B testing to optimize your website for higher conversions. Utilize ecommerce tracking and multi-channel funnels for a detailed view of your sales performance and marketing channel contributions.
Custom Reports and Dashboards:
Create custom reports and dashboards to visualize and interpret data relevant to your business goals. Use advanced filters, segments, and visualization options to gain deeper insights. Incorporate custom dimensions and metrics for tailored data analysis. Integrate external data sources to enrich your analytics and make well-informed decisions.
This guide is designed to help you harness the power of Google Analytics for making data-driven decisions that enhance website performance and achieve your digital marketing objectives. Whether you are looking to improve SEO, refine your social media strategy, or boost conversion rates, understanding and utilizing Google Analytics is essential for your success.
Bridging the Digital Gap Brad Spiegel Macon, GA Initiative.pptxBrad Spiegel Macon GA
Brad Spiegel Macon GA’s journey exemplifies the profound impact that one individual can have on their community. Through his unwavering dedication to digital inclusion, he’s not only bridging the gap in Macon but also setting an example for others to follow.
Italy Agriculture Equipment Market Outlook to 2027harveenkaur52
Agriculture and Animal Care
Ken Research has an expertise in Agriculture and Animal Care sector and offer vast collection of information related to all major aspects such as Agriculture equipment, Crop Protection, Seed, Agriculture Chemical, Fertilizers, Protected Cultivators, Palm Oil, Hybrid Seed, Animal Feed additives and many more.
Our continuous study and findings in agriculture sector provide better insights to companies dealing with related product and services, government and agriculture associations, researchers and students to well understand the present and expected scenario.
Our Animal care category provides solutions on Animal Healthcare and related products and services, including, animal feed additives, vaccination
Gen Z and the marketplaces - let's translate their needsLaura Szabó
The product workshop focused on exploring the requirements of Generation Z in relation to marketplace dynamics. We delved into their specific needs, examined the specifics in their shopping preferences, and analyzed their preferred methods for accessing information and making purchases within a marketplace. Through the study of real-life cases , we tried to gain valuable insights into enhancing the marketplace experience for Generation Z.
The workshop was held on the DMA Conference in Vienna June 2024.
Instagram has become one of the most popular social media platforms, allowing people to share photos, videos, and stories with their followers. Sometimes, though, you might want to view someone's story without them knowing.
APNIC Foundation, presented by Ellisha Heppner at the PNG DNS Forum 2024APNIC
Ellisha Heppner, Grant Management Lead, presented an update on APNIC Foundation to the PNG DNS Forum held from 6 to 10 May, 2024 in Port Moresby, Papua New Guinea.
3. JavaScript can be strange
• Syntactically similar to C++ and Java
“Java is to JavaScript as car is to carpet”
• Prototypal inheritance
• Classless. Objects inherit from objects.
• Loosely typed
• Type coercion. “Truthy” / “falsy” values.
• Objects are mutable
5. NodeLists
Get all the anchors in a page:
var anchors1 = document.getElementsByTagName('a');
[<a href="#">Item 1</a>,
<a href="#">Item 2</a>]
var anchors2 = document.querySelectorAll('a');
[<a href="#">Item 1</a>,
<a href="#">Item 2</a>]
6. NodeLists
User interaction causes more anchors to be
added to the DOM.
More content
including
anchors returned Pagination request
to server
7. NodeLists
One of our NodeLists is automatically
updated:
console.log(anchors1);
[<a href="#">Item 1</a>,
<a href="#">Item 2</a>,
<a href="#">Item 3</a>,
<a href="#">Item 4</a>]
console.log(anchors2);
[<a href="#">Item 1</a>,
<a href="#">Item 2</a>]
10. Scope and Closures
Variables are scoped to functions
var foo = "bar"; //global
function widget() {
var foo = "123"; //scoped to widget
}
11. Scope and Closures
Variables are scoped to functions
var message = 'Hello? Is anybody there?';
function helloWorld() {
var message = 'Hello, world!';
return message;
} // returns "Hello, world!"
12. Scope and Closures
Functions don't need to be named.
A common scoping technique is to use the
Immediately-Invoked Function Expression
(aka IIFE)
13. Scope and Closures
Immediately-Invoked Function Expression:
(function () {
var message = 'Hello, world!',
conferenceName = 'Dr. Dobbs India',
attendees = 'Awesome';
}());
15. Scope and Closures
Functions also create closures.
Closure = Anything declared within a function
is aware of anything else declared within that
function.
16. Scope and Closures
Functions also create closures.
var public = 'Everybody sees this.';
function family() {
var father, mother;
function kids() {
var child1, child2;
}
}
17. Scope and Closures
Building a game leveraging closures:
var game = (function () {
var secret = 5;
return function (num) {
var total = secret * num;
console.log('You say ' + num + ', I say ' +
total + '. What is my secret?');
};
}());
18. Scope and Closures
Building a game leveraging closures:
> game(5)
You say 5, I say 25. What is my secret?
> game(10)
You say 10, I say 50. What is my secret?
> secret
ReferenceError: secret is not defined
19. Scope and Closures
Block scope with let*
if (x) {
let myVar;
let yourVar = 123;
}
* Not yet available everywhere.
20. Scope and Closures
Block scope with let*
var myVar = 5;
let(myVar = 6) {
alert(myVar); // 6
}
alert(myVar); // 5
* Not yet available everywhere.
26. Memoization
var square = (function () {
var memo = [];
return function (num) {
var sqr = memo[num];
if (typeof sqr === 'undefined') {
console.log('Calculating...');
memo[num] = sqr = num * num;
}
return sqr;
}
}());
27. Memoization
var fetchData = (function () {
var data = null, timestamp = new Date().getTime();
return function (url, callback) {
if (timestamp - new Date().getTime() > 60000) {
$.ajax(url, {success: function (d) {
timestamp = new Date().getTime();
data = d;
callback(data);
});
} else {
callback(data);
}
}
}());
37. Function overloading
function calculateAverage(values) {
var total = 0;
if (!Array.isArray(values)) {
values = Array.prototype.slice.call(arguments);
}
values.forEach(function (val) {
total += val;
});
return total / values.length;
}
41. Async Code Execution
What does this code do?
// Load appointments for April
$.ajax('/calendar/2014/04/');
// Show the calendar
showCalendar();
Shows an empty calendar.
42. Async Code Execution
Ajax requests are asynchronous.
The JavaScript engine doesn’t wait.
// Load appointments for April
$.ajax('/calendar/2014/04/');
// Show the calendar
showCalendar();
43. Async Code Execution
Event-driven programming where callback
functions are assigned as event handlers.
When X happens, do Y. Where X is the event
and Y is the code to execute.
44. Async Code Execution
Assigning an Ajax event handler:
// Load appointments for April
$.ajax('/calendar/2014/04/', {
complete: showCalendar
});
45. Async Code Execution
Event handler assignment:
document.onclick = function (e) {
e = e || event;
console.log('Mouse coords: ', e.pageX, ' / ', e.pageY);
}
46. Async Code Execution
Event handler assignment:
document.addEventListener('click', function (e) {
e = e || event;
console.log('Mouse coords: ', e.pageX, ' / ', e.pageY);
});
document.addEventListener('click', function (e) {
e = e || event;
var target = e.target || e.srcElement;
console.log('Click target: ', target);
});
47. Async Code Execution
Event handler assignment:
var xhr = new XMLHttpRequest();
xhr.onload = function () {
console.log(this.responseText);
}
xhr.open('get', ’/weather_data');
xhr.send();
48. Async Code Execution
Event handler context:
document.onclick = function (e) {
// `this` refers to document object
e = e || event;
console.log('Mouse coords: ', e.pageX, ' / ', e.pageY);
}
49. Async Code Execution
Event handler context:
xhr.onload = function () {
// `this` refers to xhr object
console.log(this.responseText);
}
64. Prototypal Inheritance
“All objects in JavaScript are descended from
Object”
Object.prototype.hello = 'world';
var myObject = new Object();
Object
.hello
myObject
.hello
66. Prototypal Inheritance
They have a prototype property allowing
inheritance.
function Person() {};
Person.prototype.name = "Bob";
67. Prototypal Inheritance
You can create an instance of one using the
new keyword:
var person1 = new Person();
console.log(person1.name); // Bob
68. Prototypal Inheritance
Live link with its parent:
function Animal() {}
var dog = new Animal();
Animal.prototype.speak = function (msg) {
console.log(msg)
};
69. Prototypal Inheritance
Live link with its parent:
function Animal() {}
var dog = new Animal();
Animal.prototype.speak = function (msg) {
console.log(msg)
};
dog.speak('woof');
72. Optimization
Rather than assigning individual handlers:
var a = document.getElementById('save');
a.onclick = function () {
// save code
};
73. Optimization
Assign one for all of the same type:
document.onclick = function (e) {
e = e || event;
var target = e.target || e.srcElement;
if (target.id === 'save') {
// save code
}
};