perf: use samplesLength instead of multiple use samples.length (#59)

* perf: avoid calling `sort()` and multiple use `samples.length`

* fix: typo

* revert: sort() implementation

* revert: keep original

* feat: improve

* fix: sort

src/task.ts

@@ -112,29 +112,29 @@ export default class Task extends EventTarget {
 
     await this.bench.teardown(this, 'run');
 
-    samples.sort((a, b) => a - b);
-
     if (!this.result?.error) {
-      const min = samples[0]!;
-      const max = samples[samples.length - 1]!;
+      samples.sort((a, b) => a - b);
+
       const period = totalTime / this.runs;
       const hz = 1000 / period;
-
+      const samplesLength = samples.length;
+      const df = samplesLength - 1;
+      const min = samples[0]!;
+      const max = samples[df]!;
       // benchmark.js: https://github.com/bestiejs/benchmark.js/blob/42f3b732bac3640eddb3ae5f50e445f3141016fd/benchmark.js#L1912-L1927
       const mean = getMean(samples);
       const variance = getVariance(samples, mean);
       const sd = Math.sqrt(variance);
-      const sem = sd / Math.sqrt(samples.length);
-      const df = samples.length - 1;
+      const sem = sd / Math.sqrt(samplesLength);
       const critical = tTable[String(Math.round(df) || 1)] || tTable.infinity!;
       const moe = sem * critical;
-      const rme = (moe / mean) * 100 || 0;
+      const rme = (moe / mean) * 100;
 
       // mitata: https://github.com/evanwashere/mitata/blob/3730a784c9d83289b5627ddd961e3248088612aa/src/lib.mjs#L12
-      const p75 = samples[Math.ceil(samples.length * (75 / 100)) - 1]!;
-      const p99 = samples[Math.ceil(samples.length * (99 / 100)) - 1]!;
-      const p995 = samples[Math.ceil(samples.length * (99.5 / 100)) - 1]!;
-      const p999 = samples[Math.ceil(samples.length * (99.9 / 100)) - 1]!;
+      const p75 = samples[Math.ceil(samplesLength * 0.75) - 1]!;
+      const p99 = samples[Math.ceil(samplesLength * 0.99) - 1]!;
+      const p995 = samples[Math.ceil(samplesLength * 0.995) - 1]!;
+      const p999 = samples[Math.ceil(samplesLength * 0.999) - 1]!;
 
       if (this.bench.signal?.aborted) {
         return this;