Benchmarking

When writing libraries, a very common task that needs to be done is testing the speed of methods, usually against other libraries. Deno provides an easy-to-use subcommand for this purpose.

The most basic form of deno benchmarking is providing a name and an anonymous function to run.

Deno.bench("URL parsing", () => {
  new URL("https://deno.land");
});

We are also able to use an async function.

Deno.bench("Async method", async () => {
  await crypto.subtle.digest("SHA-256", new Uint8Array([1, 2, 3]));
});

We can optionally use long form bench definitions.

Deno.bench({
  name: "Long form",
  fn: () => {
    new URL("https://deno.land");
  },
});

We are also able to group certain benchmarks together using the optional group and baseline arguments.

Deno.bench({
  name: "Date.now()",
  group: "timing",
  baseline: true,
  fn: () => {
    Date.now();
  },
});

Deno.bench({
  name: "performance.now()",
  group: "timing",
  fn: () => {
    performance.now();
  },
});

Run this example locally using the Deno CLI:

deno bench https://github.com/denoland/deno-docs/blob/main/by-example/benchmarking.ts

Additional resources: