Develop advanced web content

JavaScript enhancements

• Class field syntax

  • Private instance fields and methods

    • use #variableName instead of _variableName

    • define methods with #methodName instead of methodName

    • applies to static fields

  • Language-enforced access protection

  • Public and private static fields

• Weak references

  • Weakly refer to an object without preventing garbage collection: use new WeakRef(object) to held a weak reference to an object

  • Get underlying object from weak reference if it exists: check via deref()? e.g. weakObject.deref()?.objectMethod();

  • Register notifications about objects garbage collection via FinalizationRegistry (warning: you may not get the callback from FinalizationRegistry right way because it runs on event loop)

• Top-level await

  • available in modules

  • use await outside of a async function at the top level

  • async modules block execution of modules importing them

• Module in workers

  • efficient resource utilization

  • ergonomic and performance benefits of modules (dynamic import, optimized loading and execution, and dependency management)

  • easy to move heavy work to background thread

  • modules are now available in different types of workers, including web worker, service worker, and worklet

• Internationalization improvements

WebAssembly updates

What’s WebAssembly?

• binary instruction format for a stack-based virtual machine

• type of a code that can be run in modern web browsers with performance close to native code

• designed to be a portable compilation target for programming languages like C, C++, or Rust

Enhancements:

• bulk memory operations

• non-trapping float-int conversions

• Sign-extension operators

• JavaScript BigInt integration

• reference types

• streaming download and compilation

New web APIs

New features/feature updates:

• WebGL 2.0

• Storage Access

• WebM

• VP9

• Media Recorder

• Audio Worklet

• Web Share

• Media Session

• Speech recognition