“JSR is a JavaScript/TypeScript registry. It is not a package manager. It is pretty clear that npm was the first viable package manager and registry for the JavaScript ecosystem. Since then we have seen a lot of innovation in the package manager side of the equation, with yarn, pnpm, and even run-times integrating that package manager like Bun. [...] There has been little change or innovation on the registry side that still has the npm registry at its core.”

Highlights:

• “JSR supports semver expression of dependencies.” This feature helps Deno – which, until now, has used exact versions.
• JSR dynamically adapts its packages to specific requests:
  • “[...] you publish your source, be it [only] TypeScript or [only] JavaScript, and the registry makes sure that the users consume the right version of code.”
  • “[...] while it isn't part of JSR at the moment, very soon JSR will generate type definitions along with transpiled JavaScript code when targeting the npm ecosystem.”
  • “The registry is runtime aware in that the package creator publishes a single version and the registry handles serving up a version specific to the target runtime [Deno, Node.js, etc.].”
• TypeScript-related features:
  • “[...] published code is ‘zapped’” – type-checked in a limited, quick way.
  • “[...] published code can be fully documented via automatic document generation.”

• Set.prototype.intersection(other)
• Set.prototype.union(other)
• Set.prototype.difference(other)
• Set.prototype.symmetricDifference(other)
• Set.prototype.isSubsetOf(other)
• Set.prototype.isSupersetOf(other)
• Set.prototype.isDisjointFrom(other)

“Browsers recently gained a new interoperable method that you can call on Arrays: Array.prototype.with().”

“This article explores how this method works and how to use it to update an array without mutating the original array.”

const ages = [10, 15, 20, 25];
const newAges = ages.with(1, 16);

console.log(newAges); // [10, 16, 20, 25]
console.log(ages); // [10, 15, 20, 25] (unchanged)

• Promise.all()
• Promise.allSettled()
• Promise.any()
• Promise.race()

• It works with JavaScript Date objects and supports time zone operations.
• “Under the hood, Tempo mines JavaScript’s Intl.DateTimeFormat to extract complex data like time zone offsets and locale aware date formats, giving you a simple API to format, parse, and manipulate dates.”

“If you’ve built projects with Vite, chances are you’ve also used Hot Module Replacement (HMR). HMR allows you to update your code without having to refresh the page, such as editing a component markup or adjusting styles, the changes are immediately reflected in the browser, which enables faster code interation and improved developer experience.”

“While HMR is also a feature in other bundlers like Webpack and Parcel, in this blog we’ll dig deeper into how it works in Vite specfically. Generally other bundlers should also work similarly.”

“To preface, HMR is not easy and certain topics may require some time to digest, but I hope to have piqued your interest!”