Six technologies that will change the web platform

Transcript

1. Six technologies that will change the web platform enterJS, 2014-06-30
2. Dr. Axel Rauschmayer, Ecmanauten.de Six web technologies 1. asm.js: near-native performance on the web 2. ParallelJS: parallelized JavaScript code 3. ECMAScript 6: evolving the language, uniting the community 4. CSS Grid Layout: native-like GUI layout 5. Installable web apps: install web apps natively 6. Web Components: a standard infrastructure for widgets 2
3. asm.js Near-native performance on the web (© Jonathan Pincas)
4. Dr. Axel Rauschmayer, Ecmanauten.de Things that slow down JavaScript • Boxing: type-tagged values must be extracted • Enables primitives and objects to coexist • JIT compilation (slow version first, fast version later) • Runtime type checks • Garbage collection • Flexible data structures 4
5. Dr. Axel Rauschmayer, Ecmanauten.de What is asm.js? • Very static and limited subset of JavaScript. • Can be compiled ahead of time, to fast code. • Foundation: JavaScript’s semantics and compiler infrastructure. • Easier to standardize • Easier to implement 5
6. Dr. Axel Rauschmayer, Ecmanauten.de An asm.js module function MyAsmModule( stdlib, foreign, heap) { "use asm"; // mark as asm.js module ! function func1(...) { ... } function func2(...) { ... } ... ! return { exportedFunc: func1, ... }; }
 Normal JavaScript function, obeying certain rules. • stdlib: access to standard library (esp. Math) • foreign: foreign function interface, access to normal JS code. • heap: instance of ArrayBuffer 6
7. Dr. Axel Rauschmayer, Ecmanauten.de Example // Compiled during loading, directly to fast code: function DiagModule(stdlib) { "use asm"; var sqrt = stdlib.Math.sqrt; function square(x) { x = +x; return +(x*x); } function diag(x, y) { x = +x; y = +y; return +sqrt(square(x) + square(y)); } return { diag: diag }; } // Link and use: var fast = DiagModule(window); // link module console.log(fast.diag(3, 4)); // 5 7
8. Dr. Axel Rauschmayer, Ecmanauten.de Static typing Variables: var a = 0; // int var b = 0.0; // double Parameters and return values: function func(x, y) { x = x|0; // int y = +y; // double return +(x * y); // returns double } 8
9. Dr. Axel Rauschmayer, Ecmanauten.de Supported types Values types:! • 64 bit doubles. +x • 32 bit integers. x|0 • 32 bit floats (ECMAScript 6). Math.fround(x) ! Reference types:! • ArrayBufferView types (to access heap): Int8Array, Uint8Array, Int16Array, Uint16Array, Int32Array, Uint32Array, Float32Array, Float64Array • Functions • Function tables (arrays of functions with same signature) • References to foreign functions 9
10. Dr. Axel Rauschmayer, Ecmanauten.de asm.js performance Emscripten: C/C++ → LLVM bitcode → asm.js • Speed: 67% of native Real-world uses: • Commercial game engine: Unreal Engine 3 • Emscripten + WebGL • Ported within a week • Recently: Unreal Engine 4 (demo)
 Engine support: • Firefox: explicit support, fastest • Others: getting faster ! ! ! 10
11. Dr. Axel Rauschmayer, Ecmanauten.de The big picture Usage:! • Fast, low-level: asm.js • Rarely hand-written (use C++, other LLVM languages, LLJS) • Pragmatic alternative to bytecode (similar, with pros + cons) • Slow, high-level: JavaScript
 JavaScript source code:! • Universal format for delivering code on the web • Abstracts over • Compilation strategies of various engines • High level vs. low level 11
12. Dr. Axel Rauschmayer, Ecmanauten.de Advantages of asm.js • Relatively easy to implement on top of existing engines • Well-integrated with JavaScript • Backward compatible 12
13. ParallelJS Parallelized JavaScript code (© terren in Virginia)
14. Dr. Axel Rauschmayer, Ecmanauten.de ParallelJS • Problem: JavaScript is still mostly sequential. • Goal: Parallelize some JS code. • Keep it simple. 14
15. Dr. Axel Rauschmayer, Ecmanauten.de New methods • Methods: • Array.prototype.mapPar() • Array.prototype.filterPar() • Array.prototype.reducePar() • Similar to traditional array methods map(), filter(), reduce() • Order in which elements are processed is undefined.
 㱺 can be parallelized 15
16. Dr. Axel Rauschmayer, Ecmanauten.de map() versus mapPar() 16 3 2 1 fork join Thread 1 9 4 1 Thread 2 Thread 3 3 2 1 Thread 1 9 4 1 Thread 2 Thread 3
17. Dr. Axel Rauschmayer, Ecmanauten.de Rules for callback parameters • Don’t mutate shared data (mutating own data is OK) • Can’t use many host objects (especially DOM) 17
18. Dr. Axel Rauschmayer, Ecmanauten.de Modes of execution • Sequentially: normal library as a fallback • Concurrently: via support in engines • SIMD: under exploration • GPU: under exploration 18
19. Dr. Axel Rauschmayer, Ecmanauten.de Executive summary: ParallelJS • Simple data parallelism for JavaScript • Limited, but safe (no locks, no concurrent write access to data) • Tentatively scheduled for ECMAScript 8 (ca. end of 2018) • Probably in engines long before 19
20. ECMAScript 6 Evolving the language, uniting the community (© Diane Yuri)
21. Dr. Axel Rauschmayer, Ecmanauten.de ECMAScript 6 • Next version of JavaScript (current: ECMAScript 5.1) • Cleans up and evolves the language • Standardized by June 2015 • Can already be used today, via cross-compilation: • TypeScript • Next versions of: Ember.js, AngularJS • etc. 21
22. Dr. Axel Rauschmayer, Ecmanauten.de ECMAScript 6 features Arguably most important for community (less fragmentation): • Classes • Modules
 Other highlights: • Block-scoped variables • Parameter default values • Destructuring (assignment, parameters) • Arrow functions (functions with lexical this) • Iterators, for-of loop • Generators • Promises • Template strings: flexible string interpolation (multi- line strings and raw strings) • Standard lib.: Map, WeakMap, Set, new methods 22
23. CSS Grid Layout Native-like GUI layout (© =Nahemoth=)
24. Dr. Axel Rauschmayer, Ecmanauten.de CSS Grid Layout • Catches up with native GUI layout
 (Android, iOS, Java SWT, …) • Better than: • Flexbox (only one dimension) • Tables (not enough control over sizing of columns and rows) • Specification edited by Google, Microsoft, Mozilla 24
25. Dr. Axel Rauschmayer, Ecmanauten.de Beyond Flexbox Can’t be decomposed into Flexboxes… 25
26. Dr. Axel Rauschmayer, Ecmanauten.de Adapt to available space 26
27. Dr. Axel Rauschmayer, Ecmanauten.de CSS #grid { display: grid; grid-template-columns: auto minmax(min-content, 1fr); grid-template-rows: auto minmax(min-content, 1fr) auto } #title { grid-column: 1; grid-row: 1 } #score { grid-column: 1; grid-row: 3 } #stats { grid-column: 1; grid-row: 2; justify-self: start } #board { grid-column: 2; grid-row: 1 / span 2; } #controls { grid-column: 2; grid-row: 3; align-self: center } • x fr: x times the remaining space (0 ≤ x ≤ 1) • auto: synonym for minmax(min-content, max-content) • Justification/alignment: stretch, baseline, start, etc. 27
28. Dr. Axel Rauschmayer, Ecmanauten.de Responsive design Portrait Landscape 28
29. Dr. Axel Rauschmayer, Ecmanauten.de CSS @media (orientation: portrait) { #grid { display: grid; grid-template-areas: "title stats" "score stats" "board board" "ctrls ctrls"; ! grid-template-columns: auto minmax(min-content, 1fr); grid-template-rows: auto auto minmax(min-content, 1fr) auto } }
 @media (orientation: landscape) { #grid { display: grid; grid-template-areas: "title board" "stats board" "score ctrls"; ! grid-template-columns: auto minmax(min-content, 1fr); grid-template-rows: auto minmax(min-content, 1fr) auto } } #title { grid-area: title } #score { grid-area: score } #stats { grid-area: stats } #board { grid-area: board } #controls { grid-area: ctrls } 29
30. Dr. Axel Rauschmayer, Ecmanauten.de Implementation status • Older version shipping in Trident (IE) • Blink (Chrome): work in progress (Google and Igalia) • WebKit (Safari): work in progress (Igalia) • Gecko (Firefox): work in progress (started early this year) 30
31. Installable web apps Install web apps natively (© FutUndBeidl)
32. Dr. Axel Rauschmayer, Ecmanauten.de Installable web apps • Install web apps as if they were native • Killer feature of web apps: can be used without installation (e.g. just once) Formats: • Hosted app: collection of web-hosted assets plus… • App manifest • Cache manifest • Packaged app (with app manifest, no cache manifest needed) • Needed for signing (and thus app stores) Publishing: • App store/marketplace! • Self-publishing 32
33. Dr. Axel Rauschmayer, Ecmanauten.de State of the art Native web app installation supported by OS: • Android • iOS • Windows Phone Generate native apps via Firefox and
 Chrome (if in Chrome Web Store): • Windows • OS X • Linux
 Web apps are native apps: • Chrome OS • Firefox OS Platforms supported by Cordova: Amazon Fire OS, Android, Firefox OS, iOS, Ubuntu, Windows Phone, Windows, and others. ! ! 33
34. Dr. Axel Rauschmayer, Ecmanauten.de Standardization • Standard app manifest: new, backed by Google and Mozilla. • Standard package format for apps and content
 㱺 in planning stage 34
35. Web Components A standard infrastructure for widgets (© trazomfreak)
36. Dr. Axel Rauschmayer, Ecmanauten.de What are Web Components? Problem:! • Writing reusable widgets for HTML is hard (example: social buttons).
 㱺 frameworks • Many incompatible frameworks! Solution:! • Web Components • Suite of APIs, provides infrastructure for widgets 36
37. Dr. Axel Rauschmayer, Ecmanauten.de Web Component APIs • Templates! • Shadow DOM: encapsulate the DOM of widgets (=nest documents) • Custom Elements: define both appearance and behavior • HTML Imports: package HTML (HTML, CSS, templates, scripts)
 㱺 useful for packaging custom elements Polyfills for current browsers: • Google Polymer • Mozilla X-Tag 37
38. Dr. Axel Rauschmayer, Ecmanauten.de Templates Built-in support for templating: <template id="mytemplate"> <img src="" alt="great image"> <div class="comment"></div> </template> • Templates can be placed almost anywhere. • Content is inactive: • Not considered part of the document
 㱺 no actions are triggered (by images, CSS, scripts) • Invisible 38
39. Dr. Axel Rauschmayer, Ecmanauten.de Templates <template id="mytemplate"> <img src="" alt="great image"> <div class="comment"></div> </template> ! ! var t = document.querySelector('#mytemplate'); ! // Fill in data t.content.querySelector('img').src = 'logo.png'; ! // Add to document var clone = document.importNode(t.content, true); document.body.appendChild(clone); 39
40. Dr. Axel Rauschmayer, Ecmanauten.de Shadow DOM • Problem: HTML and CSS of widget leaks into surrounding document (and vice versa). • IDs and classes • Style rules • Shadow DOM encapsulates HTML and CSS via nested documents. 40
41. Dr. Axel Rauschmayer, Ecmanauten.de Shadow DOM: example 1 <body> <button>Hi!</button> <script> var host = document.querySelector('button'); var root = host.createShadowRoot(); root.textContent = 'HELLO WORLD'; </script> </body> 41
42. Dr. Axel Rauschmayer, Ecmanauten.de Shadow DOM: example 2 <body> <button>Hi!</button> <script> var host = document.querySelector('button'); var root = host.createShadowRoot(); root.innerHTML = '== <content></content> =='; </script> </body> 42
43. Dr. Axel Rauschmayer, Ecmanauten.de Custom Elements • Define new HTML elements • Name: at least one dash (no namespaces needed) • Builds on the existing HTMLElement and event infrastructure 43
44. Dr. Axel Rauschmayer, Ecmanauten.de Registering a custom element var XFoo = document.registerElement('x-foo', { prototype: { __proto__: HTMLElement.prototype, ! // Lifecycle: creation of instance createdCallback: function () { ... }, ! // Lifecycle: instance inserted into document attachedCallback: function () { ... }, ! // Lifecycle: instance removed from document detachedCallback: function () { ... }, ! // Lifecycle: attribute added, removed, changed attributeChangedCallback: function ( attrName, oldVal, newVal) { ... }, } }); 44
45. Dr. Axel Rauschmayer, Ecmanauten.de Setting up content createdCallback: function () { ! // Template var t = document.querySelector('#foo-template'); var clone = document.importNode(t.content, true); ! // Shadow DOM this.createShadowRoot().appendChild(clone); }, 45
46. Dr. Axel Rauschmayer, Ecmanauten.de Using the Custom Element Declaratively, in HTML: <x-foo></x-foo> Via document.createElement(): var xFoo = document.createElement('x-foo'); xFoo.addEventListener('click', function(e) { alert('Thanks!'); }); Via the constructor: var xFoo = new XFoo(); document.body.appendChild(xFoo); 46
47. Dr. Axel Rauschmayer, Ecmanauten.de HTML Imports ! Applications: • Importing templates • Bundling CSS and JavaScript
 (think Twitter Bootstrap) • Custom Elements: bundle CSS, templates, JavaScript Importing: JavaScript: <script src="..."> CSS: <link rel="stylesheet" href="..."> HTML: HTML Imports 47
48. Dr. Axel Rauschmayer, Ecmanauten.de Packaging a Custom Element <style>...</style> <template>...</template> <script> var MyElem = document .registerElement('my-elem', ...); </script> (Also possible: CSS, template, JS via external files.) Importing the element: <link rel="import" href="my-elem.html"> 48
49. Dr. Axel Rauschmayer, Ecmanauten.de Web components in the real world • The next versions of Ember.js and AngularJS will be based on Web Components. • Blink is considering supporting the legacy <marquee> tag via a web component. • Timestamps on GitHub: via a Custom Element and Polymer polyfill. 49
50. Dr. Axel Rauschmayer, Ecmanauten.de Executive summary Web Components: • Infrastructure for a common ecosystem for widgets. • Considerable momentum: • Certain at Mozilla and Google, under consideration at Microsoft • Next versions of AngularJS, Ember.js are based on Web Components 50
51. Recap (© CollegeDegrees360)
52. Dr. Axel Rauschmayer, Ecmanauten.de Six web technologies 52 Benefit Technology Availability More speed asm.js Now ParallelJS Work in progress Broader ecosystem ECMAScript 6 (classes, modules) Now (compile to ES5) Web Components Now (polyfill) Help with GUIs and apps Web Components Now (polyfill) CSS Grid Layout Soon Installable web apps Now
53. rauschma.de (© Nate Grigg)
54. Dr. Axel Rauschmayer, Ecmanauten.de Resources • “asm.js: closing the gap between JavaScript and native” by A.R. • “ParallelJS: data parallelism for JavaScript” by A.R. • “ECMAScript 6: what’s next for JavaScript?” by A.R. (slides) • “CSS Grid Layout Module Level 1” by Tab Atkins Jr., fantasai, Rossen Atanassov (W3C Editor’s Draft) • “CSS Grid Layout. Specification overview. Implementation status and roadmap” by Manuel Rego (slides) • “Installing web apps natively” by A.R. • WebComponents.org: site with resources Bonus: “Speaking JavaScript” by A.R. (free online book) 54