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TypeScript is a typed superset of JavaScript that compiles to plain JavaScript.
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TypeScript github.com

Airbnb's tool for helping migrate code to TypeScript

ts-migrate is a tool for helping migrate code to TypeScript. It takes a JavaScript, or a partial TypeScript, project in and gives a compiling TypeScript project out.

ts-migrate is intended to accelerate the TypeScript migration process. The resulting code will pass the build, but a followup is required to improve type safety. There will be lots of // @ts-expect-error, and any that will need to be fixed over time. In general, it is a lot nicer than starting from scratch.

ts-migrate is designed as a set of plugins so that it can be pretty customizable for different use-cases. Potentially, more plugins can be added for addressing things like improvements of type quality or libraries-related things (like prop-types in React).

Marius Andra github.com

Autogenerating Kea's TypeScript support

Marius Andra added TypeScript support to his React state management library with kea-typegen:

I tried a lot of different ways to add TS support to Kea. At the end of the day what was needed was just not possible without an extra type generation step. I’ll document the failed attempts in a blog post one day. The issue boils down to the fact that each block inside a logic (e.g. reducers) gets the logic itself as a parameter (reducers: logic => (...)). That kind of loopy stuff is just not possible with TS right now. At least not to the level that it has to be for it to work in Kea (think of selectors that depend on each other). Ultimately, all of the pure-TS attempts I tried would have yielded a partial solution.

Thus kea-typegen was born. Even if it’s just a step along the way (TS compiler plugins a’la babel someday?) and still missing many features, it’s already really useful. It uses the TypeScript compiler API to analyse your source files and print out complete types (interfaces) for them.

Marius also recorded a video of the process in action.

Svelte svelte.dev

Svelte <3 TypeScript

Orta Therox, making the big announcement on behalf of the Svelte team:

We think it’ll give you a much nicer development experience — one that also scales beautifully to larger Svelte code bases — regardless of whether you use TypeScript or JavaScript.

Up until now TypeScript was usable with Svelte, but not officially supported by the project. What does that official support look like?

  • You can use TypeScript inside your <script> blocks — just add the lang="ts" attribute
  • Components with TypeScript can be type-checked with the svelte-check command
  • You get autocompletion hints and type-checking as you’re writing components, even in expressions inside markup
  • TypeScript files understand the Svelte component API — no more red squiggles when you import a .svelte file into a .ts module

I know a lot of people have been waiting for this. Congrats to all involved on a big release!

React github.com

200 bytes to never think about React state management libraries ever again

Gotta love when a library is so small that Logbot can JIT inline it in the News and save us precious clicks…

import React from "react"

export interface ContainerProviderProps {
	children: React.ReactNode
}

export interface Container<Value> {
	Provider: React.ComponentType<ContainerProviderProps>
	useContainer: () => Value
}

export function createContainer<Value>(useHook: () => Value): Container<Value> {
	let Context = React.createContext<Value | null>(null)

	function Provider(props: ContainerProviderProps) {
		let value = useHook()
		return <Context.Provider value={value}>{props.children}</Context.Provider>
	}

	function useContainer(): Value {
		let value = React.useContext(Context)
		if (value === null) {
			throw new Error("Component must be wrapped with <Container.Provider>")
		}
		return value
	}

	return { Provider, useContainer }
}

export function useContainer<Value>(container: Container<Value>): Value {
	return container.useContainer()
}

TypeScript github.com

Zero-config CLI for TypeScript package development

Despite all the recent hype, setting up a new TypeScript (x React) library can be tough. Between Rollup, Jest, tsconfig, Yarn resolutions, TSLint, and getting VSCode to play nicely….there is just a whole lot of stuff to do (and things to screw up). TSDX is a zero-config CLI that helps you develop, test, and publish modern TypeScript packages with ease–so you can focus on your awesome new library and not waste another afternoon on the configuration.

Shlomo Kraus github.com

Mockshot – automatic mock generation from snapshot tests

We made a silly joke on Twitter yesterday (this is what Twitter is for, no?) about test doubles and that unfortunate moment when they inevitably surprise you.

This prompted Shlomo Kraus to reach out and tell us about Mockshot. In brief:

Imagine you could:

  1. Never manually write a mock again
  2. Have a guarantee that your mocks are always valid

Sounds nice! It works by using Jest’s snapshot tests output to generate mocks to be used in other tests.

This is purposeful coupling, which seems like it could backfire in the long-run. However, the team behind the library has been using it for over a year and are still singing its praises. For more on their experience creating and using it, read this.

Julian Tellez github.com

Lambcycle – a declarative lambda middleware with life cycle hooks

Lambcycle is a middleware for lambda functions. It defines a configurable life-cycle and allows you to focus on your application’s logic. It has a “Feature as Plugin” approach, so you can easily create your own plugins or reuse your favorite packages with very little effort 🐑 🛵.

The author goes deep on why Lambcycle solves a serious problem over on Medium.

Kent C. Dodds Medium

Every new web app at PayPal begins with TypeScript (here's why)

Kent C. Dodds shares the backstory of paypal-scripts, a tool that encapsulates all the tools common to PayPal applications and published modules and why TypeScript was a fit. Kent took a poll in their #paypal-scripts Slack channel and 100% of respondents said they wanted the change. Here’s what happened next…

About a week later, I had totally migrated paypal-scripts from supporting Flow to supporting TypeScript (most of that time was making all the tools recognize .ts and .tsx files 🙄 and allowing paypal-scripts to dogfood itself which is kinda tricky 🐶).

Then we had Christmas break 🎄 and the week we got back after the new year 🎆, it was merged and now every new project starts off with modern tools that will stay updated by default and will be statically typed with TypeScript.

Terminal eugeny.github.io

"A terminal for a more modern age"

I put Terminus’ tagline in scare quotes because while it’s intriguing, I do not know for sure whether it delivers on that promise. In more of its own words, Terminus is:

…heavily inspired by Hyper. It is, however, designed for people who need to get things done.

Them sound like fighting words. But what does “designed for people who need to get things done” mean, exactly? From the feature list in the README, I think maybe it means that it takes Windows more seriously than Hyper and handles printing output more quickly. But that’s just a guess…

I’d love to see a roundup and comparison of this new breed of Electron-based terminals. Anybody game?

Leo Farias github.com

NearDB - a simple document db made for globally distributed reads

The motivation behind NearDB:

While working on building edge applications for higher performance and lower latency there is a need store persistent data also on edge. There are multiple distributed database solutions but they are very involved and costly while having a much lower global footprint than a CDN. The idea came up to leverage ubiquitous and mature infrastructure like cloud storage and CDNs to deliver a persistent data solution from the edge.

Kelly github.com

A boilerplate web app to build your own SaaS product

You can use this web app as a boilerplate for building your own SaaS product. The app has many common SaaS features, so you can focus on the features that differentiate your product.

As with most boilerplates, this is opinionated about its stack, which features:

React, Material-UI, Next, MobX, Express, Mongoose, MongoDB, Typescript

Here’s the full list of features and the live demo.

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