feat(fmt): display millisecond durations

rstackjs · chenjiahan · Sep 1, 2026 · Sep 1, 2026 · Sep 1, 2026 · Sep 1, 2026
commit 9bb4b21fb59e8bdf44ba608740c6e15e65234452
diff --git a/packages/rstack/src/fmt/cli.ts b/packages/rstack/src/fmt/cli.ts
@@ -8,6 +8,7 @@ import { ensureProjectCacheDir } from '../projectCache.ts';
 import { fmtCacheFileName } from './cacheStore.ts';
 import { resolveFmtConfig } from './config.ts';
 import { discoverFmtFiles } from './discovery.ts';
+import { formatElapsed } from './elapsed.ts';
 import { createRelativePathResolver, toPosixPath } from './pathHelpers.ts';
 import { runFmtFiles } from './runner.ts';
 import type { FmtMode, FmtRunResult, ResolvedFmtConfig } from './types.ts';
@@ -157,34 +158,8 @@ const createDisplayPathResolver = (
   return (filePath) => toPosixPath(resolveRelativePath(filePath));
 };
 
-const prettyTime = (seconds: number): string => {
-  const format = (time: string, unit: 'm' | 's') =>
-    color.bold(`${time}${unit}`);
-
-  if (seconds < 10) {
-    const digits = seconds >= 0.01 ? 2 : 3;
-    return format(seconds.toFixed(digits), 's');
-  }
-
-  if (seconds < 60) {
-    return format(seconds.toFixed(1), 's');
-  }
-
-  const minutes = Math.floor(seconds / 60);
-  const minutesLabel = format(minutes.toFixed(0), 'm');
-  const remainingSeconds = seconds % 60;
-
-  if (remainingSeconds === 0) {
-    return minutesLabel;
-  }
-
-  const secondsLabel = format(
-    remainingSeconds.toFixed(remainingSeconds % 1 === 0 ? 0 : 1),
-    's',
-  );
-
-  return `${minutesLabel} ${secondsLabel}`;
-};
+const prettyTime = (milliseconds: number): string =>
+  color.bold(formatElapsed(milliseconds));
 
 const formatCount = (count: number): string => color.bold(count);
 const formatFileCount = (count: number, isError = false): string => {
@@ -207,7 +182,7 @@ const logFmtResult = (
   mode: FmtMode,
   cwd: string,
   processedFileCount: number,
-  durationSeconds: number,
+  durationMilliseconds: number,
   fixCommand?: string,
 ): void => {
   let writtenCount = 0;
@@ -235,7 +210,7 @@ const logFmtResult = (
     }
 
     const processedFiles = formatFileCount(processedFileCount);
-    const time = prettyTime(durationSeconds);
+    const time = prettyTime(durationMilliseconds);
     const message =
       writtenCount > 0
         ? `Formatted ${formatCount(writtenCount)} of ${processedFiles} in ${time}.`
@@ -255,10 +230,12 @@ const logFmtResult = (
       ? `Run ${color.cyan(fixCommand)} to fix.`
       : `Rerun this command without ${color.cyan('--check')} to fix.`;
     logger.error(`Formatting issues found in ${differentFiles}. ${fixHint}`);
-    logger.info(`Checked ${processedFiles} in ${prettyTime(durationSeconds)}.`);
+    logger.info(
+      `Checked ${processedFiles} in ${prettyTime(durationMilliseconds)}.`,
+    );
   } else if (result.exitCode === 0) {
     logger.success(
-      `Checked ${formatFileCount(processedFileCount)} in ${prettyTime(durationSeconds)}. No issues found.`,
+      `Checked ${formatFileCount(processedFileCount)} in ${prettyTime(durationMilliseconds)}. No issues found.`,
     );
   }
 };
@@ -415,13 +392,13 @@ const runFmtCLI = async (
       return;
     }
 
-    const durationSeconds = (performance.now() - startTime) / 1000;
+    const durationMilliseconds = performance.now() - startTime;
     logFmtResult(
       result,
       mode,
       cwd,
       result.processedFileCount,
-      durationSeconds,
+      durationMilliseconds,
       fixCommand,
     );
     process.exitCode = result.exitCode;

diff --git a/packages/rstack/src/fmt/elapsed.ts b/packages/rstack/src/fmt/elapsed.ts
@@ -0,0 +1,35 @@
+const formatSeconds = (milliseconds: number): string => {
+  const seconds = Math.floor(milliseconds / 1000);
+  const remainder = milliseconds % 1000;
+
+  if (remainder === 0) {
+    return `${seconds}s`;
+  }
+
+  const fraction = remainder.toString().padStart(3, '0').replace(/0+$/, '');
+  return `${seconds}.${fraction}s`;
+};
+
+/** Formats elapsed milliseconds after rounding to millisecond precision. */
+const formatElapsed = (milliseconds: number): string => {
+  if (milliseconds < 1) {
+    return '<1ms';
+  }
+
+  const roundedMilliseconds = Math.round(milliseconds);
+  if (roundedMilliseconds < 1000) {
+    return `${roundedMilliseconds}ms`;
+  }
+
+  const hours = Math.floor(roundedMilliseconds / 3_600_000);
+  const minutes = Math.floor(roundedMilliseconds / 60_000) % 60;
+  const seconds = formatSeconds(roundedMilliseconds % 60_000);
+
+  if (hours > 0) {
+    return `${hours}h${minutes}m${seconds}`;
+  }
+
+  return minutes > 0 ? `${minutes}m${seconds}` : seconds;
+};
+
+export { formatElapsed };
diff --git a/packages/rstack/tests/cli/fmt/helpers.ts b/packages/rstack/tests/cli/fmt/helpers.ts
@@ -42,7 +42,10 @@ export const createCliEnv = (): NodeJS.ProcessEnv => {
 };
 
 export const normalizeDuration = (output: string): string =>
-  output.replace(/\d+m(?: \d+(?:\.\d+)?s)?|\d+(?:\.\d+)?s/g, '<duration>');
+  output.replace(
+    /<1ms|\d+ms|\d+h\d+m\d+(?:\.\d+)?s|\d+m\d+(?:\.\d+)?s|\d+(?:\.\d+)?s/g,
+    '<duration>',
+  );
 
 export const expectWriteSummary = (
   output: string,

diff --git a/packages/rstack/tests/fmt/elapsed.test.ts b/packages/rstack/tests/fmt/elapsed.test.ts
@@ -0,0 +1,18 @@
+import { expect, test } from 'rstack/test';
+import { formatElapsed } from '../../src/fmt/elapsed.ts';
+
+test.each([
+  [0, '<1ms'],
+  [0.999, '<1ms'],
+  [1, '1ms'],
+  [29.6, '30ms'],
+  [999.4, '999ms'],
+  [999.6, '1s'],
+  [1_390, '1.39s'],
+  [1_234, '1.234s'],
+  [60_000, '1m0s'],
+  [60_123, '1m0.123s'],
+  [3_661_234, '1h1m1.234s'],
+] as const)('formats %sms as %s', (milliseconds, expected) => {
+  expect(formatElapsed(milliseconds)).toBe(expected);
+});