Six technologies that will change the web platform

Six technologies that will change the web platform

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Axel Rauschmayer

June 30, 2014
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    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
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    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
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    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
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    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
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    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
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    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
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    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
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    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
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    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
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    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
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    Dr. Axel Rauschmayer, Ecmanauten.de ParallelJS • Problem: JavaScript is still

    mostly sequential. • Goal: Parallelize some JS code. • Keep it simple. 14
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    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
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    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
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    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
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    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
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    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
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    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
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    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
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    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
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    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
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    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
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    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
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    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
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    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
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    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
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    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
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    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
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    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
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    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
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    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
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    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
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    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
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    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
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    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
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    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
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    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
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    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
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    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
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    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
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    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
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    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
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    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