refactor: factor out empty function as constant (#148)

Signed-off-by: Jérôme Benoit <jerome.benoit@piment-noir.org>

Author: jerome-benoit

README.md

@@ -147,7 +147,7 @@ export type Hook = (task: Task, mode: 'warmup' | 'run') => void | Promise<void>;
     - `afterAll?: () => void | Promise<void>`: invoked once after all iterations of `fn` have finished
 - `remove(name: string)`: remove a benchmark task from the task map
 - `table()`: table of the tasks results
-- `get results(): (TaskResult | undefined)[]`: (getter) tasks results as an array
+- `get results(): (Readonly<TaskResult> | undefined)[]`: (getter) tasks results as an array
 - `get tasks(): Task[]`: (getter) tasks as an array
 - `getTask(name: string): Task | undefined`: get a task based on the name
 
@@ -163,7 +163,7 @@ function has been executed.
 - `fn: Fn`: the task function
 - `opts: FnOptions`: Task options
 - `runs: number`: the number of times the task function has been executed
-- `result?: TaskResult`: the result object
+- `result?: Readonly<TaskResult>`: the result object
 - `async run()`: run the current task and write the results in `Task.result` object property
 - `async warmup()`: warmup the current task
 - `reset()`: reset the task to make the `Task.runs` a zero-value and remove the `Task.result` object property

src/bench.ts

@@ -5,6 +5,7 @@ import {
   defaultMinimumTime,
   defaultMinimumWarmupIterations,
   defaultMinimumWarmupTime,
+  emptyFunction,
 } from './constants';
 import { createBenchEvent } from './event';
 import Task from './task';
@@ -75,10 +76,8 @@ export default class Bench extends EventTarget {
     this.iterations = options.iterations ?? this.iterations;
     this.signal = options.signal;
     this.throws = options.throws ?? this.throws;
-    // eslint-disable-next-line @typescript-eslint/no-empty-function
-    this.setup = options.setup ?? (() => {});
-    // eslint-disable-next-line @typescript-eslint/no-empty-function
-    this.teardown = options.teardown ?? (() => {});
+    this.setup = options.setup ?? emptyFunction;
+    this.teardown = options.teardown ?? emptyFunction;
 
     if (this.signal) {
       this.signal.addEventListener(
@@ -236,7 +235,7 @@ export default class Bench extends EventTarget {
   /**
    * (getter) tasks results as an array
    */
-  get results(): (TaskResult | undefined)[] {
+  get results(): (Readonly<TaskResult> | undefined)[] {
     return [...this._tasks.values()].map((task) => task.result);
   }
 

src/constants.ts

@@ -1036,3 +1036,6 @@ export const defaultMinimumIterations = 10;
 export const defaultMinimumWarmupTime = 100;
 
 export const defaultMinimumWarmupIterations = 5;
+
+// eslint-disable-next-line @typescript-eslint/no-empty-function
+export const emptyFunction = Object.freeze(() => {});

src/utils.ts

@@ -1,4 +1,4 @@
-import { tTable } from './constants';
+import { emptyFunction, tTable } from './constants';
 import type { Fn, Statistics } from './types';
 
 export const nanoToMs = (nano: number) => nano / 1e6;
@@ -51,8 +51,8 @@ export const isFnAsyncResource = (fn: Fn | undefined | null): boolean => {
     if (promiseLike) {
       // silence promise rejection
       try {
-        // eslint-disable-next-line @typescript-eslint/no-empty-function, @typescript-eslint/no-unnecessary-condition
-        (fnCall as Promise<unknown>).then(() => {})?.catch(() => {});
+        // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
+        (fnCall as Promise<unknown>).then(emptyFunction)?.catch(emptyFunction);
       } catch {
         // ignore
       }