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JavaScript for Cats

JavaScript for Cats
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JavaScript Garden Although JavaScript deals fine with the syntax of two matching curly braces for blocks, it does not support block scope; hence, all that is left in the language is function scope. function test() { // a scope for(var i = 0; i < 10; i++) { // not a scope // count } console.log(i); // 10} There are also no distinct namespaces in JavaScript, which means that everything gets defined in one globally shared namespace. Each time a variable is referenced, JavaScript will traverse upwards through all the scopes until it finds it. In the case that it reaches the global scope and still has not found the requested name, it will raise a ReferenceError. The Bane of Global Variables // script Afoo = '42'; // script Bvar foo = '42' The above two scripts do not have the same effect. Again, that is not at all the same effect: not using var can have major implications. // global scopevar foo = 42;function test() { // local scope foo = 21;}test();foo; // 21 Local Variables var foo = 3; bar = 4;}test(10); Hoisting

Dix ans de pratique Javascript à Paris | Édition N°47 Je m’appelle Noëlie et je développe du Javascript depuis 2002. J’ai travaillé sur des sites à fort trafic, sur des outils de back-office et des applications mobile ou tablette. L’intitulé de mon poste est très difficile à définir car, bien que je fasse du développement Javascript, je me préoccupe avant tout du rendu final dans le navigateur. Ce métier est appelé développeur front-end ou front-office.La conception en règle générale est pour moi une vraie passion. Elle s’étend également au domaine des objets physiques : je partage toutes mes créations sur mon blog. J’aimerais vous raconter l’impact qu’ont eues les évolutions de Javascript sur mon métier de développeur à Paris. Le Javascript est un langage qui permet de toucher à beaucoup de domaines : du fonctionnement d’une interface à la manipulation de données, les possibilités sont multiples ! Intégrateur : Il travaille avec HTML et CSS mais pas avec Javascript. Du DHTML de fin 2003 à début 2005 2009 : l’explosion de HTML5

Callback Hell Truthy and Falsy: When All is Not Equal in JavaScript JavaScript variables are loosely/dynamically typed and the language doesn’t care how a value is declared or changed. 2017.08.22: This article has been updated to reflect the current state of the JavaScript ecosystem. let x; x = 1; x = '1'; x = [1]; Seemingly different values equate to true when compared with == (loose or abstract equality) because JavaScript (effectively) converts each to a string representation before comparison: A more obvious false result occurs when comparing with === (strict equality) because the type is considered: Internally, JavaScript sets a value to one of six primitive data types: Undefined (a variable with no defined value)Null (a single null value)Boolean (true or false)Number (this includes Infinity and NaN – not a number!) Everything else is an Object — including arrays. Truthy and Falsy As well as a type, each value also has an inherent boolean value, generally known as either truthy or falsy. The following values are always falsy: Everything else is truthy. 1.

Javascript - Accueil Private Members in JavaScript Douglas Crockford JavaScript is the world's most misunderstood programming language. Some believe that it lacks the property of information hiding because objects cannot have private instance variables and methods. But this is a misunderstanding. Objects JavaScript is fundamentally about objects. If a value is a function, we can consider it a method. Objects can be produced by constructors, which are functions which initialize objects. Public The members of an object are all public members. In the constructor This technique is usually used to initialize public instance variables. function Container(param) { this.member = param; } So, if we construct a new object var myContainer = new Container('abc'); then myContainer.member contains 'abc'. In the prototype This technique is usually used to add public methods. Container.prototype.stamp = function (string) { return this.member + string; } So, we can invoke the method myContainer.stamp('def') which produces 'abcdef'. Private Closures

70 Free JavaScript Books Best free JavaScript books: ECMAScript, jQuery, and other. Download ebooks (pdf, mobi, epub) and read online. Update of December 2017 collection. 6 new books. JavaScript, often abbreviated as JS, is a high-level, dynamic, weakly typed, prototype-based, multi-paradigm, and interpreted programming language. Practical ES6 Ideal for professional software developers with a basic understanding of JavaScript, this practical book shows you how to build small, interconnected ES6 JavaScript modules that emphasize reusability. Understanding ECMAScript 6 ECMAScript 6 is coming, are you ready? Exploring ES2016 and ES2017 This book covers the latest versions of JavaScript as they are created. Exploring ES6 An in-depth book on ECMAScript 6, for JavaScript programmers. ECMAScript 6 Succinctly ECMAScript 6 (ES6), also known as ECMAScript 2015, brings new functionality and features to the table that developers have been wanting for a long time. About the book JavaScript Notes For Professionals Build Pacman Author

Standard ECMA-262 Standard ECMA-262 ECMAScript® 2017 Language Specification 8th edition (June 2017) This Standard defines the ECMAScript 2017 general-purpose programming language. The following files can be freely downloaded: Kindly note that the normative copy is the HTML version; the PDF version has been produced to generate a printable document. This 8th edition has been prepared under the Ecma RF patent policy. The latest drafts are available at: Please find hereafter the place to file bugs: The previous replaced "historical" editions of this Ecma Standard are available here. Quick tip: using HTML5 localstorage to store JSON objects on a device in your PhoneGap app I’ve written a couple of articles about loading remote data into PhoneGap apps (sans framework), but I haven’t mentioned a good little method of storing that data on the device so you don’t need to request it from a server again. This is a quick tip for how you can do that. Of course, it depends on the type of data that you are loading from your server in the first place. You wouldn’t necessarily want to store data that would be out of date quickly – such as share prices or live sports scores. But there will certainly be times when you want to save the data you’ve just loaded for use at a later time, without having to load it again. Loading data from a remote source When loading data from a remote source I’d use jQuery or Zepto’s ajax() function like this: In this example I’m accessing a fictional data source to load a news article. Once the article is loaded the user might browse another article but later on may return to read this particular one again. HTML5 local and session storage

How to Avoid DOM Blocking by localStorage and Other Culprits JavaScript programs run on a single thread in the browser and in runtimes such as Node.js. When code is executing in a browser tab, everything else stops: menu commands, downloads, rendering, DOM updates and even GIF animations. This is rarely evident to the user because processing occurs quickly in small chunks. JavaScript code can’t wait for something to occur; imagine the frustration if an app froze every time it made an Ajax request. In the following example, a handler function is executed when a button click event occurs which animates an element by applying a CSS class. document.getElementById('clickme').addEventListener('click', handleClick); function handleClick(e) { let sprite = document.getElementById('sprite'); if (! ES2015 provided Promises and ES2017 introduced async/await to make coding easier, but callbacks are still used below the surface. Blocking Bandits Unfortunately, some JavaScript operations will always be synchronous, including: Web Workers The web worker script:

10 Interview Questions Every JavaScript Developer Should Know — JavaScript Scene Good to hear: Classes: create tight coupling or hierarchies/taxonomies.Prototypes: mentions of concatenative inheritance, prototype delegation, functional inheritance, object composition. Red Flags: No preference for prototypal inheritance & composition over class inheritance. Learn More: 4. OOP Pros: It’s easy to understand the basic concept of objects and easy to interpret the meaning of method calls. OOP Cons: OOP Typically depends on shared state. FP Pros: Using the functional paradigm, programmers avoid any shared state or side-effects, which eliminates bugs caused by multiple functions competing for the same resources. FP also tends to favor declarative and denotational styles, which do not spell out step-by-step instructions for operations, but instead concentrate on what to do, letting the underlying functions take care of the how. Red flags: 5. This is a trick question. Rarely, almost never, or never. Any other response. 6. There is more than one type of prototypal inheritance: 7. 8.