Phasis

Phasis is a pure-PHP JavaScript engine. It lexes, parses, and executes ECMAScript in the host PHP process — without exec('node …'), without FFI, and without binary extensions beyond ext-mbstring (always shipped) and ext-bcmath (default on every mainstream PHP build). ext-intl is optional. ext-curl enables outbound fetch().

• Embeddable — drop a JS runtime into any PHP app, framework, or CLI tool via the Phasis\Engine class.
• Spec-compliant — passes the official test262 suite at 100 %, every category, no skips.
• Web APIs — full Web Platform Pack (URL, TextEncoder/Decoder, atob/btoa, structuredClone, performance, DOMException), full Fetch Pack (fetch, Request, Response, Headers, Body, AbortController/Signal, Blob, File, FormData, EventTarget, full WHATWG Streams, navigator), plus crypto + SubtleCrypto, WebSocket, XMLHttpRequest, and a real event loop. 100 % of imported Web Platform Tests pass.
• Modern surface — arrow functions, classes, async/await, Promises, generators, Symbol, BigInt, Proxy, Reflect, Temporal, Intl, TypedArrays, full module support.
• Direct PHP↔JS interop — share PHP objects with JS without serialization. Bind PHP closures as JS functions and mutate PHP arrays from JS in place.

Why Phasis exists

PHP applications that need to run user-supplied JavaScript — templating engines, frontend SSR shims, data-validation rules, content sandboxes, headless test runners — usually shell out to Node.js or skip the feature. Either path adds operational complexity: a second runtime, a serialization boundary, a network of subprocess pipes, and a hostile deployment story for shared hosting.

Phasis closes that gap. Your PHP code can lex, parse, and execute JavaScript using only the standard library plus mbstring + bcmath. The engine ships as a Composer package, runs anywhere PHP 8.2+ runs, and exposes a single small API surface.

What it does

• Implements the full ECMAScript standard library: Array, String, Object, Math, JSON, Date, RegExp, Map, Set, Promise, Proxy, Reflect, Symbol, BigInt, TypedArray, Temporal, Intl, generators, async iterators, modules.
• Ships the Web Platform APIs that real-world JS libraries pre-check for: URL, URLSearchParams, TextEncoder/TextDecoder, atob/btoa, structuredClone, performance, DOMException. See Web APIs for the full surface.
• Ships fetch with the full Fetch family — Request, Response, Headers, body consumers, AbortController/AbortSignal, Blob, File, FormData, EventTarget/Event, and full WHATWG Streams (ReadableStream, WritableStream, TransformStream, BYOB, queuing strategies). Real HTTP works out of the box via PHP's ext-curl.
• Ships crypto + full SubtleCrypto (SHA family, HMAC, AES-GCM/CBC/CTR, RSA-OAEP/PSS/PKCS1, ECDSA, ECDH, HKDF, PBKDF2), WebSocket (RFC 6455 + swappable transport), and XMLHttpRequest (layered over the same fetch transport).
• Ships a real event loop: setTimeout, setInterval, clearTimeout, clearInterval, queueMicrotask, plus Stage-3 AsyncContext for value propagation across async boundaries.
• Supports modern syntax — destructuring, spread/rest, computed properties, optional chaining, nullish coalescing, template literals, tagged templates, classes (with private fields, static blocks, decorators), top-level await.
• Bridges PHP and JS values losslessly. Pass a PHP object into JS and mutations are visible to PHP. Pass a PHP callable and JS sees it as a function.
• Sandboxes execution. Resource limits cover call depth, loop iterations, string length, console output, and wall-clock time. The host controls the runtime, including the fetch transport and policy hooks.
• Verifies every change against Node.js (V8). Compliance is measured continuously against the official test262 suite plus the Web Platform Tests in CI on every push.

What it is not

Phasis is not a JIT compiler. It is a tree-walking interpreter with an opportunistic bytecode VM. Expect ~100× the runtime of V8 on dispatch-bound workloads. The trade-off is zero dependencies, pure PHP, and host-controlled execution — perfect for embedding JavaScript into PHP apps where correctness and isolation matter more than raw throughput.

Where to start

• Getting Started — install and run your first script.
• CLI — bin/phasis for running files, evaluating expressions, and the REPL.
• API — embed Phasis\Engine in your PHP app.
• Interop — share PHP values and objects with JavaScript.
• Compatibility — test262 coverage and supported features.
• Advanced — architecture, bytecode VM, benchmarks, and the oracle testing model.