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function

jsc.profile

function profile<T extends (...args: any[]) => any>(
callback: T,
sampleInterval?: number,
...args: Parameters<T>
): ReturnType<T> extends Promise<U> ? Promise<SamplingProfile> : SamplingProfile;

Run JavaScriptCore's sampling profiler for a particular function

This is pretty low-level.

Things to know:

  • LLint means "Low Level Interpreter", which is the interpreter that runs before any JIT compilation
  • Baseline is the first JIT compilation tier. It's the least optimized, but the fastest to compile
  • DFG means "Data Flow Graph", which is the second JIT compilation tier. It has some optimizations, but is slower to compile
  • FTL means "Faster Than Light", which is the third JIT compilation tier. It has the most optimizations, but is the slowest to compile