How can you write fast JavaScript for V8?
Keep object shapes stable (same hidden class), keep functions monomorphic (same argument types), use dense arrays, avoid delete/eval/with, use const/let, break long tasks into chunks, use requestAnimationFrame for animations, debounce/throttle rapid events, and use Web Workers for heavy computation.
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More FAQs in Performance Tips for V8 JavaScript
V8 assigns hidden classes based on object shape (property names and order). Objects with the same hidden class share optimized code. Different shapes cause deoptimization, which falls back to slower bytecode.
delete changes the object's hidden class, triggering a deoptimization. Instead of deleting a property, set it to null or undefined. This preserves the hidden class and keeps the optimized code path.
A function that always receives the same argument types (same hidden classes). V8 can optimize it with inline caching and TurboFan. If the function receives mixed types (polymorphic), V8 deoptimizes and falls back to slower bytecode.
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