TypeScript
@typescript
16 Mar 2023
TypeScript 5.0 is here! 🎉🎉

Learn about what's new and try it today!

devblogs.microsoft.com/typescript/ann…
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TypeScript
@typescript
16 Mar 2023
Replying to @typescript
Want to know what's new in TypeScript 5.0 at a glance? Here's a thread about what's packed into this release that makes it great. 🧵

x.com/typescript/sta…
TypeScript
@typescript
16 Mar 2023
TypeScript 5.0 is here! 🎉🎉

Learn about what's new and try it today!

devblogs.microsoft.com/typescript/ann…
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TypeScript
@typescript
16 Mar 2023
Replying to @typescript
We'll make this one fast: TypeScript's now way speedier.

You can expect at anywhere from 10%-20% of your compile times to disappear with TypeScript 5.0!
Chart of build/run times TypeScript 5.0 relative to TypeScript 4.9: material-ui docs build time: 90% Playwright build time: 88% tsc startup time: 87% tsc build time: 87% Outlook Web build time: 82% VS Code build time: 80%
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@typescript
16 Mar 2023
Replying to @typescript
TypeScript's also lighter too! Unzipped from npm, TypeScript 5.0 now takes about 41% less space compared to TypeScript 4.9!
Chart of package size on npm between TypeScript 4.9 and 5.0. 4.9 package size is 63.8 MB, 5.0 package size is 37.4 MB.
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TypeScript
@typescript
16 Mar 2023
Replying to @typescript
Ever gotten into an argument about decorating? Now you can decorate without any red flags. 🚩🚩🚩🚩

TypeScript 5.0 ships the latest version of decorators! ✨

Use them without setting --experimentalDecorators 🧪.
class Greeter { message: string; constructor(message: string) { this.message = message; } @bound greet() { console.log(this.message); } } const greeter = new Greeter("sup?"); const greet = greeter.greet; greet();/** * Ensures a method is bound to every instance. */ function bound(method: Function, context: ClassMethodDecoratorContext<any>) { if (context.private) { throw new Error("Cannot bind private methods."); } context.addInitializer(function (this) { this[context.name] = method.bind(this); }); }
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TypeScript
@typescript
16 Mar 2023
Replying to @typescript
If you thought TypeScript 4.9 was a satisfying release...

5.0 will do it again by bringing support for

/** @⁠satisfies */

to checked JavaScript files!

Works the same as our recent 'satisfies' operator in TypeScript files.
/** * @satisfies {Record<string, (e: Event) => void>} */ export let eventHandlers = { // type of 'e' is inferred as 'Event' click: (e) => { e.preventDefault(); }, scroll: (e) => { }, }; // ✅ works eventHandlers.click(new Event("click")); // ❌ error eventHandlers.clock(new Event("click"));
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TypeScript
@typescript
16 Mar 2023
Replying to @typescript
TypeScript 5.0 brings '--moduleResolution bundler' to model how most modern bundlers and loaders work.

It understands classic Node-style resolution while respecting rules for 'exports', 'imports', etc. in your dependencies.
To model how bundlers work, TypeScript now introduces a new strategy: `--moduleResolution bundler`. ``` { "compilerOptions": { "target": "esnext", "moduleResolution": "bundler" } } ``` If you are using a modern bundler like Vite, esbuild, swc, Webpack, Parcel, and others that implement a hybrid lookup strategy, the new `bundler` option should be a good fit for you.

Mar 16, 2023 · 7:12 PM UTC

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TypeScript
@typescript
16 Mar 2023
Replying to @typescript
If you're a library author, maybe you've told your users to write 'as const' when they call a function.

With 'const' type parameters, you can hint which values should get literal &amp; read-only types.
declare function frozen<const T>(x: T): T; // inferred type is 'readonly ["elsa", "anna", "olaf"]' let itSnow = frozen([ "elsa", "anna", "olaf" ]);
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@typescript
16 Mar 2023
Replying to @typescript
Does your linter fight with your editor?

We're lovers, not fighters. Let's all get along. ☮️✌️

TypeScript 5.0 is smarter about respecting upper/lower-casing in already-sorted imports.
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TypeScript
@typescript
16 Mar 2023
Replying to @typescript
We're pretty sure you love coding with TypeScript - but just in *case*, we added a new feature to our code-completions.

If you write a 'switch' statement and you're using literal types, we'll scaffold out all your 'case's automagically. 🪄
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TypeScript
@typescript
16 Mar 2023
Replying to @typescript
Speaking of literal types - every enum member now acts kind of like a literal type. This is way safer, and pushes us to be tidy and consistent. 🤓
enum E { A = 42, } // still works let fine: E = 42; // ❌ now an error let oops: E = 43;
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TypeScript
@typescript
16 Mar 2023
Replying to @typescript
TypeScript 5.0 also makes it possible to mix and match options from different 'tsconfig.json' files.
// tsconfig1.json { "compilerOptions": { "strictNullChecks": true } } // tsconfig2.json { "compilerOptions": { "noImplicitAny": true } } // tsconfig.json { "extends": ["./tsconfig1.json", "./tsconfig2.json"], "files": ["./index.ts"] }
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TypeScript
@typescript
16 Mar 2023
Replying to @typescript
And there's lots more which you can read here on our blog!

devblogs.microsoft.com/typescript/ann…
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