ES2015 / ES6: Basics of modern Javascript
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The document outlines the evolution and key features of modern JavaScript, particularly focusing on ES2015 (ES6) as the latest version of ECMAScript. It discusses the goals of ES6, its syntax improvements, and practical applications such as promises and modules. The document emphasizes the importance of using transpilers like Babel to enable ES6 features in current browsers and encourages gradual learning of ES6 functionalities.
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ES2015 / ES6: Basics of modern Javascript
- 1. ES2015 / ES6 Basics of modern JavaScript Wojciech Dzikowski @DzikowskiW
- 2. • working remotely for a software startup Folium Partners since 2011 • we create software for ebook and audiobook publishers • Software engineer : JavaScript, PHP (Symfony 2), Android, OS X / iOS • contact: @DzikowskiW Wojciech Dzikowski
- 3. Agenda 1. Evolution of JavaScript 2. Main goals of JavaScript and ES6 3. ES6 in practice (selected features) 4. Q&A
- 4. Dictionary • JavaScript (JS) - a high-level, dynamic, untyped, and interpreted programming language created originally for web browsers, ECMAScript implementation • ECMA International - an international non-profit standards organization for information and communication systems.It acquired its current name in 1994, when the European Computer Manufacturers Association (ECMA) changed its name to reflect the organization's global reach and activities • ECMAScript (ES)- scripting-language specification standardized by Ecma International in ECMA-262 and ISO/IEC 16262. Well-known implementations of the language, such as JavaScript, JScript and ActionScript have come into wide use for client-side scripting on the Web • ES2015 (ES6) - the newest version of ECMAScript
- 6. 90s • 1995: Netscape creates Mocha • 1995: Mocha -> LiveScript -> JavaScript • 1996: ECMA adopts JavaScript • 1997: ECMA-262 (ES1) • 1998: ES2 • 1999: ES3 (regex, try/catch)
- 7. 90s • browser wars IE vs Netscape • DHTML, “animate everything” • forms validation • visitor counters • code had to be optimised per browser (IE vs Netscape)
- 8. 2000-2004 • browser wars - IE wins • not much going on in JS world
- 9. 2005: AJAX • Broadband Internet becomes popular • Asynchronus server requests (AJAX) becomes popular • renaissance of JavaScript • countless libraries (mainly helping with AJAX requests and DOM operations)
- 10. 2006-2009 • 2008: ECMAScript4 (abandoned) • 2009: ECMAScript 3.1 5 (strict, JSON, Reflect) • 2009: servers welcome JavaScript: Node.js
- 11. 2010-2015 • frameworks evolution, no longer just DOM & AJAX helpers • JS packet managers: npm, bower • solutions for keeping code in modules (node.js, CommonJS, AMD, Browserify) • JavaScript preprocessors (Grunt, Gulp, Webpack,…)
- 12. Now • 2015: ECMAScript 2015 (lots of features) • since 2015 a new ES spec will be released each year • upcoming: ES2016 (no major changes)
- 14. JavaScript - pros • easy syntax • functions are objects (awesome!) • independent from any big company • the only native web browser language • big and vibrant community • lots of helpful tools, libraries and frameworks
- 15. JavaScript
- 16. JavaScript ≠ Java Guinea pig ≠ pig ≠ ≠
- 17. JavaScript - cons (subjective list) • differences in comparison to Java-like languages can create confusion (prototypes vs classes,function scope vs block scope, hoisting, +, …)
- 18. JavaScript - cons (subjective list) • not many unequivocal clean code practices (each framework = new practices, enforcing bad practices can be harmful to community) • very rapid development often makes tools and frameworks obsolete fast, it is hard to choose frameworks and tools for apps that need to be maintained for years
- 19. Main goals of ES6 • fix (some of) ES5 problems • backwards compatibility (ES5 code is valid in ES6) • modern syntax • better suited for big applications • new features in standard library
- 21. ES6 in browsers today • ES6 => ES5 transpilers
- 22. Babel - usage • command line: $ babel es6.js -o es5.js • Online: • Konfigurator: http://babeljs.io/docs/setup/
- 23. Babel - użycie • Online wizard: http://babeljs.io/docs/setup/
- 24. ES6 in practice
- 25. ES5: var
- 26. ES5: var - hoisting
- 27. ES6: let is new var
- 28. ES5…
- 29. …ES6: const
- 34. ES6: Classes
- 35. ES6: Classes
- 36. ES6: Setters & getters
- 39. ES5 recap: filter
- 44. ES5: for … in • best practice: avoid that loop
- 45. ES6: for … of • for … of can iterate not only over arrays • Homework: Iterators in ES6
- 46. Asynchronus programming • common in JS (animations, server requests, etc.) • Classic solution: callback • Problem: only one callback per async task
- 47. Async programming, ES5 • Problem: Nested functions create messy code
- 48. Async programming, ES5 • Second try: Listeners • Problem: no reaction when async function ends before listener registers, often hard to debug
- 49. ES6: Promise • object that keeps a result of an async function (waiting, resolved, rejected) • fixes earlier problem with listeners, since callback is called even if async function completed the task earlier • allows to return (Promise) objects and work with them, even if async function is still not completed (better code readability) • “promises” that it will get resolved • uses Observer pattern to populate the result • flattens nested promises to avoid “callback hell”
- 50. Promises Promise • waiting • resolved • rejected States: async function Listener 1 Listener 2 Listener 3
- 51. Promises
- 53. Promises
- 54. Modules (ES5) • IIFE (Immediately Invoked Function Expression) • controls variable exposure
- 55. Modules (ES6) in browser • use tools such as Browserify / Webpack, • native ES6 modules are not yet implemented
- 56. What we have learned? • let/const • template strings • new ways to declare objects • classes • map, filter, reduce (ES5) • arrow functions • for … of • Promises • Modules
- 57. Other ES6 features • Proxy • Iterators • Generators • Symbols • Map/Set, WeakMap/WeakSet • extended standard library (Number, Math, Array)
- 58. Summary • use transpilers (Babel) to write ES6 today for any browser • learn ES6 step by step, you don’t have to know everything at once • many features are syntactic sugar, use with moderation • ES6 is now, go learn it!
- 59. What next? • Babel docs: https://babeljs.io/docs/learn-es2015/ • Mozilla docs: http://developer.mozilla.org/en-US/ docs/Web/JavaScript • ES specs: https://github.com/tc39/ecma262 • Pluralsight: JavaScript Fundamentals for ES6 • Youtube: FunFunFunction
- 60. Q&A