---
title: "Jest 23, TypeScript 2.9, and an alternative to Babel"
publication: "JavaScript Weekly"
issue: 388
published_at: "2018-06-01"
canonical_url: "https://javascriptweekly.com/issues/388"
---

This week's JavaScript news       

#388 — June 1, 2018 

[Read on the Web](https://javascriptweekly.com/issues/388)   

JavaScript Weekly   

I'm in San Francisco next week exhibiting and speaking at [DevXCon](https://2018.devxcon.com/) about JavaScript Weekly :-) It's a developer relations conference, so if you know any DevRel people located near SF, let them know as I believe some tickets are still available. 

Due to next week's travel, JavaScript Weekly will lean on submissions more than usual, so if you want to submit stuff for us to consider [use this nifty submissions form](https://cooperpress.typeform.com/to/QbNInP) or just hit reply :-) Thanks!
 _— Peter Cooper, editor_    

[Jest 23 Released: Even Faster JS Testing](https://facebook.github.io/jest/blog/2018/05/29/jest-23-blazing-fast-delightful-testing.html) — [Jest](https://facebook.github.io/jest/en/) is a popular JavaScript testing tool and when [webpack](https://webpack.js.org/) switched from Mocha to the Jest 23 beta, they saw a 6x speed improvement for their test suite.. There’s also [a talk about Jest 23](https://www.youtube.com/watch?v=cAKYQpTC7MA&feature=youtu.be&t=1881) if you prefer a video guide. 

Rick Hanlon II   

[Simplifying Web Worker Code with Comlink](https://davidea.st/articles/comlink-simple-web-worker) — Web Workers help you offload work from the main thread to other threads but they can be tricky to manage. This tutorial presents a solution (from Google, no less): [Comlink](https://github.com/GoogleChromeLabs/comlink), a small RPC library. 

David East   [![\](https://copm.s3.amazonaws.com/1cb9f6ab.png)](https://circleci.com/blog/how-to-design-services-for-continuous-deployment-3-best-practices/?utm_source=cooperpress&utm_medium=newsletter&utm_campaign=june18&utm_content=javascript-weekly) 

[How to Design Services for Continuous Deployment: 3 Best Practices](https://circleci.com/blog/how-to-design-services-for-continuous-deployment-3-best-practices/?utm_source=cooperpress&utm_medium=newsletter&utm_campaign=june18&utm_content=javascript-weekly) — The benefits of continuous delivery are well-documented elsewhere. In this post I want to share some of the practices that we use at CircleCI to ensure that our services can safely be deployed continuously. 

CircleCI sponsor   

[A JavaScript String Methods Cheatsheet](https://gist.github.com/rauschma/c46fc10f671ed5bf14021bc14f101c8d) — A very handy reference covering not _quite_ every string method but certainly the truly useful ones. 

Dr. Axel Rauschmayer   

[TypeScript 2.9 Released](https://blogs.msdn.microsoft.com/typescript/2018/05/31/announcing-typescript-2-9/) — The JavaScript superset that brings optional static types to JS takes another step forward at both the editor support and language level. One new feature is `import()` types which [this article explains.](https://davidea.st/articles/typescript-2-9-import-types) _If you’re totally new to TypeScript, [this is a good primer.](https://auth0.com/blog/typescript-practical-introduction/)_ 

Microsoft   

[Sucrase: A Super-Fast Alternative to Babel.. in Certain Situations](https://github.com/alangpierce/sucrase) — Compiles down to modern JS runtimes only (rather than ES5) and focuses on compiling down JSX, TypeScript and Flow which results in a smaller scope with more performance optimizations to be had. 

Alan Pierce   

[UTC is Enough for Everyone, Right?](https://zachholman.com/talk/utc-is-enough-for-everyone-right) — A really neat article that goes from the history of time itself through to standardization and working with time in both JavaScript and HTML. 

Zach Holman   

[Deno: A Secure TypeScript Runtime on V8 6.8](https://github.com/ry/deno) — An interesting idea from the original creator of Node.js, Ryan Dahl. It’s built with Go, is _not_ Node or npm compatible, and is.. ‘segfaulty’ :-) 

Ryan Dahl  

💻 Jobs  

[Sr. Fullstack Engineer (Remote)](https://www.stickermule.com/careers) — Sticker Mule is looking for passionate developers to join our remote team. Come help us become the Internet’s best place to shop and work. 

Sticker Mule   

[JavaScript Expert? Sign Up for Vettery](https://www.vettery.com/tech?utm_source=newsletter&utm_medium=cooper-javascriptweekly&utm_term=tech&utm_content=grouped&utm_campaign=ad-42051) — Top companies use Vettery to find the best tech talent. Take a few minutes to join our platform. 

Vettery  

🎬 Videos, Screencasts and Talks  

[On React Suspense](https://www.youtube.com/watch?v=z-6JC0_cOns) — A look at React’s vision for async rendering. 

Andrew Clark   

[Azure Tips and Tricks Video Series](https://www.youtube.com/channel/UCi00MP5k2uxC3ZFxylwQtuA) — Collection of short videos on using the Azure platform. New videos are released weekly. [Subscribe now](https://www.youtube.com/channel/UCi00MP5k2uxC3ZFxylwQtuA). 

Azure sponsor   

[Using Async Generators to Stream Data in JavaScript](https://www.youtube.com/watch?v=wrI-Jb0oFyk) 

Fun Fun Function  

📘 Tutorials  

[From Vanilla JS to Vue.js: A Refactoring Tale](https://hackernoon.com/from-vanillajs-to-vue-js-a-refactoring-tale-846bee20ba3d) 

Peter Mbanugo   

[Creating UIs with Angular Material Design Components](https://www.sitepoint.com/angular-material-design-components/) — How to create a simple Angular app with a UI built from Angular Material components. 

Ahmed Bouchefra   

[Transparent Wrapper Components in Vue](https://zendev.com/2018/05/31/transparent-wrapper-components-in-vue.html) 

Kevin Ball   

[Revising Useful JavaScript Array and Object Methods](https://codeburst.io/useful-javascript-array-and-object-methods-6c7971d93230) — Write cleaner code by making use of modern array and object methods. 

Robert Cooper   

[Deploy Your Webpack Apps to Heroku in 3 Simple Steps](https://codeburst.io/deploy-your-webpack-apps-to-heroku-in-3-simple-steps-4ae072af93a8) 

Rajesh Babu   

[Live Session: Learn to Build a Slack Integration](https://buildingwithactions.splashthat.com/jsweekly) — Join us June 12 for a live demo of Slack’s new developer features. Tune in from anywhere, & bring questions. 

Slack sponsor   

[GraphQL: Everything You Need to Know](https://medium.com/@weblab_tech/graphql-everything-you-need-to-know-58756ff253d8) — Not _directly_ about JavaScript but this did very well on our [@JavaScriptDaily](https://twitter.com/javascriptdaily) Twitter, so why not? 

Weblab Technology   

[From npm to yarn and Back (to npm) Again](https://mixmax.com/blog/to-yarn-and-back-again-npm) — When seeking better performance is a bit like switching lines at the grocery store. 

Mixmax Engineering Blog  

🔧 Code and Tools  

[Critters: Webpack Plugin to Inline Critical CSS and Lazy-Load the Rest](https://github.com/GoogleChromeLabs/critters) 

Google Chrome Labs   

[CurrencyFormatter.js: Easy Formatting of Values in 155 Currencies](https://osrec.github.io/currencyFormatter.js/) — Contains 155 currency and 715 locale definitions out of the box. 

OSREC Financial   

[Eager Code Evaluation Done Right](https://quokkajs.com/?utm_source=cooperpress&utm_medium=email&utm_content=javascriptweekly&utm_name=javascriptweekly) 

Wallaby.js sponsor   

[jquery-calendar: A Responsive jQuery Calendar Scheduler Built with Bootstrap and Moment.js](https://github.com/ArrobeFr/jquery-calendar) — It’s not often we get to include something about jQuery these days! 

Arrobe   

[Minipack: A Simplified Example of a Module Bundler Written in JS](https://github.com/ronami/minipack) — The aim is to show how most bundlers work under the hood. 

Ronen Amiel   

[Subliminal: An Opinionated Minimalistic VS Code Theme for JS](https://github.com/gaearon/subliminal) 

Dan Abramov   

[Mermaid: Generate Diagrams and Flowcharts From Text](https://github.com/knsv/mermaid) — Converts text to diagrams and flowcharts (a la Markdown). [GitHub repo.](https://github.com/knsv/mermaid) 

Knut Sveidqvist   

[Proppy: Functional Props Composition for UI Components](https://proppyjs.com/) — Can integrate with React, Vue, Preact, Redux, and RxJS. 

Fahad Ibnay Heylaal         

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