Add --du flag, fix -s to match Linux tree behavior, and clean up codebase

- Add --du flag for recursive directory size accumulation (like du -c)
- Fix -s/sizes to use stat.size directly instead of recursive sums,
  matching Linux tree -s behavior
- Remove dirsOnly check from isExcluded (already handled by
  filterAndOrderContents)
- Add JSDoc comments documenting assumptions to all functions
- Fix terminology inconsistencies across CLI, README, and source
- Extract resolveOptions() to deduplicate option merging logic
- Unify callback parameter names in filterAndOrderContents to 'entry'

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: yangshun

README.md

@@ -59,7 +59,7 @@ Usage:
   $ tree <command> [options]
 
 Options:
-  -a, --all-files           All files, include hidden files, are printed.
+  -a, --all-files           All files, including hidden files, are printed.
   -D, --date                Show last modification time for each entry.
   -f, --full-path           Print the full path prefix for each file.
   -i, --no-indent           Print entries without tree indentation lines.
@@ -70,6 +70,8 @@ Options:
   --dirs-first              List directories before files.
   -d, --dirs-only           List directories only.
   -s, --sizes               Print the size of each file in bytes along with the name.
+  --du                      For each directory report its size as the accumulation
+                            of sizes of all its files and sub-directories. Implies -s.
   -I, --exclude <patterns>  Exclude files that match the pattern. | separates
                             alternate patterns. Wrap your entire pattern in double
                             quotes. E.g. "node_modules|coverage".
@@ -144,7 +146,7 @@ console.log(result);
 
 | Field           | Default                    | Type       | Description                                                                                                                           |
 | --------------- | -------------------------- | ---------- | ------------------------------------------------------------------------------------------------------------------------------------- |
-| `allFiles`      | `false`                    | `boolean`  | All files are printed. By default, tree does not print hidden files (those beginning with a dot).                                     |
+| `allFiles`      | `false`                    | `boolean`  | All files, including hidden files, are printed.                                                                                       |
 | `date`          | `false`                    | `boolean`  | Show last modification time for each entry.                                                                                           |
 | `dirsFirst`     | `false`                    | `boolean`  | List directories before files.                                                                                                        |
 | `fullPath`      | `false`                    | `boolean`  | Print the full path prefix for each file.                                                                                             |
@@ -153,11 +155,12 @@ console.log(result);
 | `quote`         | `false`                    | `boolean`  | Quote filenames in double quotes.                                                                                                     |
 | `prune`         | `false`                    | `boolean`  | Remove empty directories from output.                                                                                                 |
 | `dirsOnly`      | `false`                    | `boolean`  | List directories only.                                                                                                                |
-| `sizes`         | `false`                    | `boolean`  | Show filesizes as well.                                                                                                               |
+| `sizes`         | `false`                    | `boolean`  | Print the size of each file in bytes along with the name.                                                                             |
+| `du`            | `false`                    | `boolean`  | For each directory, report its size as the accumulation of sizes of all its files and sub-directories. Implies `sizes`.                |
 | `exclude`       | `[]`                       | `RegExp[]` | An array of regex to test each filename against. Matching files will be excluded and matching directories will not be traversed into. To exclude a directory's contents while still showing the directory itself, use a regex that matches the path with a trailing slash (e.g., `/node_modules\//`). |
 | `maxDepth`      | `Number.POSITIVE_INFINITY` | `number`   | Max display depth of the directory tree.                                                                                              |
 | `reverse`       | `false`                    | `boolean`  | Sort the output in reverse alphabetic order.                                                                                          |
-| `trailingSlash` | `false`                    | `boolean`  | Appends a trailing slash behind directories.                                                                                          |
+| `trailingSlash` | `false`                    | `boolean`  | Append a `/` for directories.                                                                                                         |
 | `lineAscii`     | `false`                    | `boolean`  | Turn on ASCII line graphics.                                                                                                          |
 | `filesFirst`    | `false`                    | `boolean`  | List files before directories.                                                                                                        |
 | `sortBy`        | `'name'`                   | `string`   | Sort the output. Options: `'name'`, `'version'`, `'mtime'`, `'ctime'`, `'size'`.                                                      |

TODO.md

@@ -59,7 +59,7 @@ Track progress of implementing Linux `tree` options in tree-node-cli.
 ## Code Improvements
 
 - [x] **Filter before stat** — `statEntries` stats all entries including hidden files that will be filtered out when `allFiles: false`. Filter hidden files before stat'ing to avoid unnecessary syscalls.
-- [ ] **Match Linux `tree -s` size behavior** — `computeSizes` recursively sums file sizes into parent directories, but Linux `tree -s` shows each entry's own `stat.size` (inode size for directories, not recursive sum). Remove `computeSizes` and use `stat.size` directly.
+- [x] **Match Linux `tree -s` size behavior** — `computeSizes` recursively sums file sizes into parent directories, but Linux `tree -s` shows each entry's own `stat.size` (inode size for directories, not recursive sum). `-s` now uses `stat.size` directly; recursive sums moved to new `--du` flag.
 - [x] **Merge `EXCLUDED_PATTERNS` into exclude** — The hardcoded `.DS_Store` pattern is checked in a separate loop for every entry. Merge it into the user's `exclude` array at initialization to simplify `isExcluded`.
 - [x] **Clarify `dirsOnly` filtering** — `dirsOnly` is checked in both `isExcluded` (skips files early) and `filterAndOrderContents` (filters file entries). The `isExcluded` check is a performance optimization that avoids stat'ing files, but the dual responsibility could be clearer.
 - [x] **Avoid mutating input arrays** — `sortContents` calls `contents.sort()` which mutates the caller's array in place. Using `[...contents].sort(...)` would be safer, though not currently a bug since callers don't reuse the array.

src/__snapshots__/index.test.ts.snap

@@ -157,9 +157,9 @@ exports[`tree > combined: filesFirst + reverse 1`] = `
 `;
 
 exports[`tree > combined: trailingSlash + lineAscii + sizes 1`] = `
-"13B single-level/
+"128B single-level/
 |-- 13B alpha.txt
-\`-- 0B beta/"
+\`-- 96B beta/"
 `;
 
 exports[`tree > default 1`] = `
@@ -421,6 +421,108 @@ exports[`tree > dirsOnly 11`] = `
 
 exports[`tree > dirsOnly 12`] = `"varied-sizes"`;
 
+exports[`tree > du 1`] = `
+"24B chain
+└── 24B alpha
+    └── 24B alpha
+        └── 24B alpha
+            └── 24B alpha
+                └── 24B alpha
+                    └── 24B alpha
+                        └── 24B alpha
+                            └── 24B alpha
+                                └── 24B alpha.txt"
+`;
+
+exports[`tree > du 2`] = `
+"29B double-level
+├── 9B alpha.txt
+└── 20B beta
+    └── 20B alpha.txt"
+`;
+
+exports[`tree > du 3`] = `"0B empty-dir"`;
+
+exports[`tree > du 4`] = `
+"30B hidden-files
+├── 8B another.txt
+└── 8B visible.txt"
+`;
+
+exports[`tree > du 5`] = `
+"5B mixed-content
+├── 1B alpha.txt
+├── 1B bravo-dir
+│   └── 1B inner.txt
+├── 1B charlie.txt
+├── 1B delta-dir
+│   └── 1B inner.txt
+└── 1B echo.txt"
+`;
+
+exports[`tree > du 6`] = `
+"68B multi-files
+├── 5B alpha.txt
+├── 17B beta.txt
+└── 46B charlie.txt"
+`;
+
+exports[`tree > du 7`] = `
+"127B multi-level
+├── 10B alpha.txt
+├── 48B beta
+│   ├── 27B alpha
+│   │   ├── 16B alpha.txt
+│   │   └── 11B beta
+│   │       └── 11B alpha.txt
+│   ├── 9B beta.txt
+│   └── 12B charlie
+│       └── 12B alpha.txt
+├── 54B charlie
+│   ├── 13B alpha.txt
+│   ├── 18B beta
+│   │   └── 18B alpha.txt
+│   └── 23B charlie.txt
+└── 15B delta.txt"
+`;
+
+exports[`tree > du 8`] = `
+"0B numbered-files
+├── 0B file1.txt
+├── 0B file10.txt
+├── 0B file2.txt
+├── 0B file20.txt
+└── 0B file3.txt"
+`;
+
+exports[`tree > du 9`] = `
+"5B single-file
+└── 5B alpha.txt"
+`;
+
+exports[`tree > du 10`] = `
+"13B single-level
+├── 13B alpha.txt
+└── 0B beta"
+`;
+
+exports[`tree > du 11`] = `
+"4B unicode-names
+├── 1B café.txt
+├── 1B emoji-🎉.txt
+├── 1B über.txt
+└── 1B 日本語
+    └── 1B ファイル.txt"
+`;
+
+exports[`tree > du 12`] = `
+"11.1kB varied-sizes
+├── 10kB large.txt
+├── 1kB medium.txt
+├── 100B small.txt
+└── 1B tiny.txt"
+`;
+
 exports[`tree > exclude 1`] = `
 "chain
 └── alpha
@@ -1161,72 +1263,72 @@ exports[`tree > reverse 12`] = `
 `;
 
 exports[`tree > sizes 1`] = `
-"24B chain
-└── 24B alpha
-    └── 24B alpha
-        └── 24B alpha
-            └── 24B alpha
-                └── 24B alpha
-                    └── 24B alpha
-                        └── 24B alpha
-                            └── 24B alpha
+"96B chain
+└── 96B alpha
+    └── 96B alpha
+        └── 96B alpha
+            └── 96B alpha
+                └── 96B alpha
+                    └── 96B alpha
+                        └── 96B alpha
+                            └── 96B alpha
                                 └── 24B alpha.txt"
 `;
 
 exports[`tree > sizes 2`] = `
-"29B double-level
+"128B double-level
 ├── 9B alpha.txt
-└── 20B beta
+└── 96B beta
     └── 20B alpha.txt"
 `;
 
-exports[`tree > sizes 3`] = `"0B empty-dir"`;
+exports[`tree > sizes 3`] = `"96B empty-dir"`;
 
 exports[`tree > sizes 4`] = `
-"30B hidden-files
+"192B hidden-files
 ├── 8B another.txt
 └── 8B visible.txt"
 `;
 
 exports[`tree > sizes 5`] = `
-"5B mixed-content
+"224B mixed-content
 ├── 1B alpha.txt
-├── 1B bravo-dir
+├── 96B bravo-dir
 │   └── 1B inner.txt
 ├── 1B charlie.txt
-├── 1B delta-dir
+├── 96B delta-dir
 │   └── 1B inner.txt
 └── 1B echo.txt"
 `;
 
 exports[`tree > sizes 6`] = `
-"68B multi-files
+"160B multi-files
 ├── 5B alpha.txt
 ├── 17B beta.txt
 └── 46B charlie.txt"
 `;
 
 exports[`tree > sizes 7`] = `
-"127B multi-level
+"192B multi-level
 ├── 10B alpha.txt
-├── 48B beta
-│   ├── 27B alpha
+├── 160B beta
+│   ├── 128B alpha
 │   │   ├── 16B alpha.txt
-│   │   └── 11B beta
+│   │   └── 128B beta
 │   │       └── 11B alpha.txt
 │   ├── 9B beta.txt
-│   └── 12B charlie
+│   └── 96B charlie
 │       └── 12B alpha.txt
-├── 54B charlie
+├── 192B charlie
 │   ├── 13B alpha.txt
-│   ├── 18B beta
+│   ├── 96B beta
 │   │   └── 18B alpha.txt
 │   └── 23B charlie.txt
 └── 15B delta.txt"
 `;
 
 exports[`tree > sizes 8`] = `
-"0B numbered-files
+"224B numbered-files
 ├── 0B file1.txt
 ├── 0B file10.txt
 ├── 0B file2.txt
@@ -1235,27 +1337,27 @@ exports[`tree > sizes 8`] = `
 `;
 
 exports[`tree > sizes 9`] = `
-"5B single-file
+"96B single-file
 └── 5B alpha.txt"
 `;
 
 exports[`tree > sizes 10`] = `
-"13B single-level
+"128B single-level
 ├── 13B alpha.txt
-└── 0B beta"
+└── 96B beta"
 `;
 
 exports[`tree > sizes 11`] = `
-"4B unicode-names
+"192B unicode-names
 ├── 1B café.txt
 ├── 1B emoji-🎉.txt
 ├── 1B über.txt
-└── 1B 日本語
+└── 96B 日本語
     └── 1B ファイル.txt"
 `;
 
 exports[`tree > sizes 12`] = `
-"11.1kB varied-sizes
+"192B varied-sizes
 ├── 10kB large.txt
 ├── 1kB medium.txt
 ├── 100B small.txt

src/cli.test.ts

@@ -241,6 +241,18 @@ describe('cli', () => {
     }
   });
 
+  test('respects --du', async () => {
+    const { stdout } = await run([
+      '--du',
+      path.join(FIXTURES_PATH, 'single-file'),
+    ]);
+    // --du implies -s, so sizes should be shown
+    const lines = stdout.split('\n');
+    for (const line of lines) {
+      expect(line).toMatch(/\dB/);
+    }
+  });
+
   test('respects -v version sort', async () => {
     const { stdout } = await run([
       '-v',

src/cli.ts

@@ -12,7 +12,7 @@ const PATTERN_SEPARATOR = '|';
 const cli = cac('tree');
 
 cli
-  .option('-a, --all-files', 'All files, include hidden files, are printed.')
+  .option('-a, --all-files', 'All files, including hidden files, are printed.')
   .option('-D, --date', 'Show last modification time for each entry.')
   .option('-f, --full-path', 'Print the full path prefix for each file.')
   .option('-i, --no-indent', 'Print entries without tree indentation lines.')
@@ -26,6 +26,10 @@ cli
     '-s, --sizes',
     'Print the size of each file in bytes along with the name.',
   )
+  .option(
+    '--du',
+    'For each directory report its size as the accumulation of sizes of all its files and sub-directories. Implies -s.',
+  )
   .option(
     '-I, --exclude <patterns>',
     'Exclude files that match the pattern. | separates alternate patterns. ' +
@@ -87,6 +91,7 @@ const options: Options = {
   ...(opts.prune != null && { prune: opts.prune as boolean }),
   ...(opts.quote != null && { quote: opts.quote as boolean }),
   ...(opts.sizes != null && { sizes: opts.sizes as boolean }),
+  ...(opts.du != null && { du: opts.du as boolean }),
   ...(opts.exclude != null && {
     exclude: (opts.exclude as string)
       .split(PATTERN_SEPARATOR)

src/formats/json.test.ts

@@ -8,6 +8,7 @@ const DEFAULT_OPTIONS: RequiredOptions = {
   date: false,
   dirsFirst: false,
   dirsOnly: false,
+  du: false,
   filesFirst: false,
   fullPath: false,
   noIndent: false,

src/formats/text.test.ts

@@ -8,6 +8,7 @@ const DEFAULT_OPTIONS: RequiredOptions = {
   date: false,
   dirsFirst: false,
   dirsOnly: false,
+  du: false,
   filesFirst: false,
   fullPath: false,
   noIndent: false,