v0.1.32728 Sep 2026·Rendering, JavaScript & JIT

Loops keep their speed when a helper ignores an argument, and JavaScript behaves more like the reference browser

A loop that calls a small helper no longer loses its compiled machine code just because it hands the helper a null, an options object or something else the helper never reads, which made such loops up to 50 times slower. Alongside it, a round of JavaScript behaviour found by checking Floati against the reference browser: class constructors, getters on array items, frozen arrays and the arguments of older-style functions now all behave the way the reference browser does.

Parity with the reference browser

74overall, as of v0.1.343

Web APIs / DOM surface42

Security architecture66

GPU / graphics acceleration68

DevTools / extensions72

Networking85

Media85

Accessibility85

Real-world site compatibility99

HTML parsing100

CSS parsing + selectors100

Layout: block / flex / grid / tables / writing-modes100

Paint + visual100

JavaScript language100

JavaScript performance (JIT)100

HTML parsing100

What changed 6 changes

JavaScript & JIT	Loops stay on compiled code when a helper ignores an argument. Floati compiles a hot loop, and the small functions it calls, into machine code, but only when it can tell what every value in the loop is. A value passed to a helper that never uses it (a null for an optional parameter, an options object the fast path skips) used to stop the whole loop from compiling. Such values are now simply passed along without being looked at: a loop calling a helper with a null went from 156 to 3 milliseconds per million calls.
JavaScript & JIT	Method calls on objects built inside a loop are faster. The safety check that confirms an object's methods have not been swapped out now reads its answer directly instead of asking the engine each time, which made a class-heavy benchmark about 19 percent faster and steadier from build to build.
Rendering	Class constructors work like the reference browser. Calling a class without new now throws the same error the reference browser throws, and a parent class sees which class is actually being built (new.target), which libraries use to set up subclasses. Reflect.construct honours the class you ask it to build, a class written as var K = class {} is named K, and a class can extend null.
JavaScript & JIT	Getters and setters on array items. Object.defineProperty can now put a getter or setter on an array position, as some libraries do for lazily computed lists. Reading the item runs the getter everywhere: in loops, in join, map, slice, spread and JSON. A missing array item also looks up the prototype chain in compiled code, as it always did in the interpreter.
JavaScript & JIT	Frozen and sealed arrays stay frozen. Object.freeze, Object.seal and Object.preventExtensions did nothing to arrays before. Writes, deletes, length changes and methods like push and sort are now refused exactly as the reference browser refuses them, silently in ordinary code and with the reference browser's error in strict code.
Rendering	The arguments of older-style functions stay linked. In a function written without strict mode, changing a parameter now changes arguments[0] and the other way round, as the language defines and older libraries rely on. Only functions that could notice the difference pay for it; the rest keep every speedup.