Skip to content

Latest commit

 

History

History
49 lines (41 loc) · 2.84 KB

supported-language.md

File metadata and controls

49 lines (41 loc) · 2.84 KB
Raw

Supported Language

To date, only a (small) subset of the JavaScript language is supported in Microvium. Basically, Microvium as it stands is meant to be a more-friendly alternative to something like EmbedVM.

Supported Language features

Note: the most up-to-date authority on supported features is the set of test scripts, each file of which is a stand-alone Microvium script that exercises a series of features in the language.

  • Basic control flow statements (if/else, while, do..while, for)
  • Primitive operators (+, ++, -, --, /, %, *, **, &, |, >>, >>>, <<, ^, ===, !==, >, <, >=, <=, !, ~, ? :, typeof), with the exception that inequality operators (>, <, >=, <=) only work on numbers at the moment.
  • Variable declarations: var, let, and const
  • Nested functions (closures) and function/arrow expressions
  • Dynamically-sized arrays and objects (with limitations, see the next section), computed properties (o[p]).
  • Function and method calls (f(), o.m(), o[m]()), this
  • Primitive literals and simple globals: true/false, 42, "hello", undefined, null, NaN, Infinity
  • Object and array literals ({...} and [...]).
  • Modules, with import and export statements
  • throw, try, and catch (but not finally)
  • Reflect.ownKeys (enumerate the keys of an object)
  • Uint8Array as a lightweight buffer type
  • Some class features: class declarations, constructors and methods.
  • See also supported builtins

NOT Supported

Some notable JavaScript features that are NOT supported in Microvium (some of these may be supported in the future):

  • void, delete, and in operators.
  • Option chaining operators like x?.y
  • Nullish coalescing operator ??
  • The increment/decrement operators aren't supported on expressions that have computed properties, such as obj[x]++.
  • Class inheritance (extends, super) and computed class members (but you can assign directly to the class prototype if you need to).
  • instanceof
  • Class expressions
  • Most of the builtin functions and objects. For example, there is no Array.prototype.map or Uint8Array.prototype.map.
  • finally
  • Iterators and for..of
  • for..in (for object key iteration, use Reflect.ownKeys)
  • Sloppy equality (==, !=)
  • arguments, with
  • Regular expressions
  • BigInt, symbols, WeakMaps
  • Destructuring, spread, rest, and default parameters
  • Generators, Promises, async/await
  • require or dynamic import
  • eval
  • globalThis

Note: any deviation of Microvium from the ECMAScript standard (including unsupported features) is subject to change and should not be relied upon.