What Is a Benchmark Builder?
A benchmark builder measures and compares synchronous JavaScript approaches. Each case runs in its own disposable Web Worker, so it cannot access the page DOM or storage, and the worker is terminated when it finishes, is cancelled, or exceeds the time limit. Results report operations per second, average execution time, and relative speed.
How to Run Benchmarks
- 1Enter synchronous JavaScript in each benchmark case and give every approach a descriptive name.
- 2Add cases as needed, choose a maximum iteration count, and click Run Benchmark.
- 3Review per-case errors or timeouts without losing successful results from the other workers.
- 4Compare ops/sec, average time, run count, and the visual bars in the results.
Common Use Cases
Algorithm Comparison
Compare different implementations of the same algorithm to find the fastest approach.
String Manipulation
Test whether string concatenation, template literals, or array join is faster for your use case.
Data Structure Selection
Benchmark Map vs Object, Set vs Array, or different iteration methods.
Frequently asked questions
How accurate are the results?
Results use performance.now() with microsecond precision and include warmup runs. However, JavaScript benchmarking in a browser can be affected by garbage collection, JIT compilation, and other factors.
Is the code executed safely?
Each case runs locally in a disposable Web Worker rather than the page. The worker has no DOM or local storage access, common network and nested-worker APIs are blocked, and a time limit terminates stuck cases. This is isolation for benchmarking, not a security boundary for code from an untrusted author.
Can I benchmark async code?
No. Measurements cover synchronous work completed during each function call. Promises, timers, and network-dependent tasks are not awaited and need a benchmark harness designed for asynchronous code.