ECMAScript 2026

The Temporal API

The Temporal API in JavaScrit 2026 provides standard objects and functions for working with dates and times.

From ES2026, the Temporal API is the standard for modern date and time management in JavaScript, designed to replace the legacy Date object.

Unlike Date, Temporal objects are immutable and provide first-class support for time zones and non-Gregorian calendars.

Resource Management with using

JavaScript 2026 added two keywords to automatically manage and dispose resources (like file handles or database connections) when they go out of scope, reducing the need for explicit try...finally blocks.

• using provides synchronous cleanup of block-scoped variables.
• await using provides asynchronous cleanup for resources like network streams.

Error Detection with Error.isError()

Error.isError() is a static method to reliably check if a value is an Error object, improving error handling and debugging.

New Array with Array.fromAsync()

Array.fromAsync() is a feature that allows developers to create a new Array instance from asynchronous iterables, array-like objects, or Promises, streamlining the handling of data from async sources.

New Uint8Array Methods in ES2026

Base64 and Hexadecimal Encodings for Uint8Array.

These new static methods facilitate working with binary data by adding direct conversion between Uint8Array objects and Base64 or hexadecimal strings.

• Uint8Array fromBase64()
  Creates a Uint8Array object from a base64-encoded string
• Uint8Array toBase64()
  Returns a base64-encoded string from the data in an int8Array
• Uint8Array fromHex()
  Creates a Uint8Array object from a hexadecimal string
• Uint8Array toHex()
  Returns a hex-encoded string from the data in an int8Array

Explicit Resource Management

The using Keyword

The using keyword is an addition to JavaScript 2026. It provides a mechanism for managing resources that require explicit disposal.

It declares a block-scoped variable, similar to const, but with the difference that it guarantees synchronous disposal of the used resource when the variable goes out of scope.

The using keyword simplifies resource management by automatically handling the cleanup process, reducing the risk of resource leaks and improving code readability compared to manual try...finally blocks for disposal.

• Resource Management
  using is designed for objects that implement the Symbol.dispose method, which defines the cleanup logic for the resource.

• Synchronous Disposal
  When a variable declared with using exits its scope (at the end of a block or function), its Symbol.dispose method is automatically called.

• Asynchronous Disposal
  For resources requiring asynchronous cleanup, the await using declaration can be employed. This ensures that the disposal process is awaited before the variable fully goes out of scope.

• Block-Scoped
  Like const, variables declared with using are local to the block in which they are declared, and must be initialized at the time of declaration.

• Immutable
  Like to const, variables declared with using cannot be reassigned after initialization.

Browser Support

using is already supported in many browsers:

Explicit Resource Management

await using

Inspired by other languages, JavaScript 2026 introduces using blocks for automatic cleanup of resources like file handles, database connections, or network streams.

This is especially beneficial for asynchronous operations:

Browser Support

await using is already supported in many browsers:

Error.isError()

The Error.isError() static method checks whether a value is an Error object.

Error.isError() is a safe alternative to instanceof Error which fails across realms.

Realm-safe error check:
An Error from an iframe verifies with Error.isError() and fails with instanceof.

Browser Support

Error.isError() is already supported in many browsers:

Array.fromAsync()

Browser Support

Array.fromAsync() is already supported in many browsers:

Uint8Array to/fromBase64()

Browser Support

to/fromBase64() is already supported in many browsers:

Uint8Array to/fromHex()

Browser Support

to/fromHex() is already supported in many browsers: