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Using JavaScript from the Future in Your Rails Applications Today Steve Kinney, @stevekinney

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Hi. I'm Steve. @stevekinney | [email protected]

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Every programming language has its creation myth.

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Turbolinks 3

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Working with JavaScript has traditionally involved memorizing a bunch of weird tricks and hacks.

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Towards a better language on the client.

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ECMAScript 6

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ECMAScript 6 2015

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So, what's in this fancy new language?

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Classes, modules, array comprehension, generators, iterators, promises, tail call optimization, proxies, string interpolation, unicode support, maps, sets, symbols, new APIs for primitive types, binary and octal literals, slides with too many words on them…

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Firming up the foundation of the language.

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let's have a little talk about var.

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let: It's like var but it does the thing you think it's going to do.

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const

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Turing students ask: “Hey Steve, what's your least favorite thing about writing JavaScript?”

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I hate string concatenation with the fiery passion of a thousand burning suns.

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Template strings to the rescue.

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JavaScript: ${…} Ruby: #{…}

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Let's play a game.

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There are some solutions to this problem, but none of them are going to make you feel good.

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Gross.

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In ES5, we got Function.prototype.bind.

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In ES6, we get arrow functions.

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What's the point of multi-line arrow functions if I need to return stuff? What gives?

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Arrow functions also lexically bind this.

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Let's do some refactoring.

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But, that's not all…

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In which, JavaScript gets some class.

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This seems brittle. Can we refactor this?

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What about inheritance?

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There is still a bit more refactoring that we can do here.

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Other goodies: class methods and properties, inheriting from built-in types, computed method names.

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Splat and spread.

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Default Arguments

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How long am I going to have to wait until I can use this stuff?

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You can use all of this and more today.

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Transpilation.

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ECMAScript 6 2015

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ECMAScript 7 2016

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The Birth of a Standard • Stage 0 - Strawman • Stage 1 - Proposal • Stage 2 - Draft • Stage 3 - Candidate • Stage 4 - Finished

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Classes, modules, array comprehension, generators, iterators, promises, tail call optimization, proxies, string interpolation, unicode support, maps, sets, symbols, new APIs for primitive types, binary and octal literals, slides with too many words on them…

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Thank you! Oh, also: Questions? All the places on the Internet: @stevekinney Come be our friend and mentor our students. Hire our students: http://people.turing.io/