Support negation-only patterns

Fixes #237

Author: sindresorhus

index.d.ts

@@ -150,7 +150,7 @@ Find files and directories using glob patterns.
 
 Note that glob patterns can only contain forward-slashes, not backward-slashes, so if you want to construct a glob pattern from path components, you need to use `path.posix.join()` instead of `path.join()`.
 
-@param patterns - See the supported [glob patterns](https://github.com/sindresorhus/globby#globbing-patterns).
+@param patterns - See the supported [glob patterns](https://github.com/sindresorhus/globby#globbing-patterns). Supports negation patterns to exclude files. When using only negation patterns (like `['!*.json']`), globby implicitly prepends a catch-all pattern to match all files before applying negations.
 @param options - See the [`fast-glob` options](https://github.com/mrmlnc/fast-glob#options-3) in addition to the ones in this package.
 @returns The matching paths.
 
@@ -163,6 +163,17 @@ const paths = await globby(['*', '!cake']);
 console.log(paths);
 //=> ['unicorn', 'rainbow']
 ```
+
+@example
+```
+import {globby} from 'globby';
+
+// Negation-only patterns match all files except the negated ones
+const paths = await globby(['!*.json', '!*.xml'], {cwd: 'config'});
+
+console.log(paths);
+//=> ['config.js', 'settings.yaml']
+```
 */
 export function globby(
 	patterns: string | readonly string[],

index.js

@@ -269,6 +269,12 @@ const createFilterFunction = isIgnored => {
 const unionFastGlobResults = (results, filter) => results.flat().filter(fastGlobResult => filter(fastGlobResult));
 
 const convertNegativePatterns = (patterns, options) => {
+	// If all patterns are negative, prepend a positive catch-all pattern
+	// This makes negation-only patterns work intuitively (e.g., '!*.json' matches all files except JSON)
+	if (patterns.length > 0 && patterns.every(pattern => isNegativePattern(pattern))) {
+		patterns = ['**/*', ...patterns];
+	}
+
 	const tasks = [];
 
 	while (patterns.length > 0) {

readme.md

@@ -9,6 +9,7 @@ Based on [`fast-glob`](https://github.com/mrmlnc/fast-glob) but adds a bunch of
 - Promise API
 - Multiple patterns
 - Negated patterns: `['foo*', '!foobar']`
+- Negation-only patterns: `['!foobar']` → matches all files except `foobar`
 - Expands directories: `foo` → `foo/**/*`
 - Supports `.gitignore` and similar ignore config files
 - Supports `URL` as `cwd`
@@ -332,6 +333,26 @@ Just a quick overview.
 - `{}` allows for a comma-separated list of "or" expressions
 - `!` at the beginning of a pattern will negate the match
 
+### Negation patterns
+
+Globby supports negation patterns to exclude files. There are two ways to use them:
+
+**With positive patterns:**
+```js
+await globby(['src/**/*.js', '!src/**/*.test.js']);
+// Matches all .js files except test files
+```
+
+**Negation-only patterns:**
+```js
+await globby(['!*.json', '!*.xml'], {cwd: 'config'});
+// Matches all files in config/ except .json and .xml files
+```
+
+When using only negation patterns, globby implicitly prepends `**/*` to match all files, then applies the negations. This means `['!*.json', '!*.xml']` is equivalent to `['**/*', '!*.json', '!*.xml']`.
+
+**Note:** The prepended `**/*` pattern respects the `dot` option. By default, dotfiles (files starting with `.`) are not matched unless you set `dot: true`.
+
 [Various patterns and expected matches.](https://github.com/sindresorhus/multimatch/blob/main/test/test.js)
 
 ## Related

tests/generate-glob-tasks.js

@@ -121,7 +121,7 @@ test('combine tasks', async t => {
 
 	t.deepEqual(
 		await getTasks(t, ['!a']),
-		[],
+		[{patterns: ['**/*'], ignore: ['a']}],
 	);
 
 	t.deepEqual(
@@ -209,15 +209,25 @@ test('random patterns', async t => {
 		const allPatterns = tasks.flatMap(({patterns}) => patterns);
 		const allIgnore = tasks.flatMap(({ignore}) => ignore);
 
+		// When there are only negative patterns, we auto-add '**/*' as a positive pattern
+		const isNegationOnly = positivePatterns.length === 0 && negativePatterns.length > 0;
+		const expectedPatternCount = isNegationOnly ? 1 : positivePatterns.length;
+
 		t.is(
 			new Set(allPatterns).size,
-			positivePatterns.length,
+			expectedPatternCount,
 			`positive patterns should be in patterns: ${patternsToDebug}`,
 		);
 
+		// When there are only negative patterns, all of them go into ignore (including negativePatternsAtStart)
+		// Otherwise, negativePatternsAtStart are discarded
+		const expectedIgnoreCount = isNegationOnly
+			? negativePatterns.length
+			: negativePatterns.length - negativePatternsAtStart.length;
+
 		t.is(
 			new Set(allIgnore).size,
-			negativePatterns.length - negativePatternsAtStart.length,
+			expectedIgnoreCount,
 			`negative patterns should be in ignore: ${patternsToDebug}`,
 		);
 	}

tests/globby.js

@@ -233,8 +233,19 @@ test('respect patterns order', async t => {
 	t.deepEqual(await runGlobby(t, ['!*.tmp', 'a.tmp']), ['a.tmp']);
 });
 
-test('return [] for all negative patterns', async t => {
-	t.deepEqual(await runGlobby(t, ['!a.tmp', '!b.tmp']), []);
+test('negation-only patterns match all files in cwd except negated ones', async t => {
+	// When using negation-only patterns in a scoped directory, it should match all files except the negated ones
+	t.deepEqual(await runGlobby(t, ['!a.tmp', '!b.tmp'], {cwd: temporary}), ['c.tmp', 'd.tmp', 'e.tmp']);
+});
+
+test('single negation-only pattern in scoped directory', async t => {
+	const result = await runGlobby(t, '!a.tmp', {cwd: temporary});
+	t.deepEqual(result, ['b.tmp', 'c.tmp', 'd.tmp', 'e.tmp']);
+});
+
+test('negation-only with brace expansion in scoped directory', async t => {
+	const result = await runGlobby(t, '!{a,b}.tmp', {cwd: temporary});
+	t.deepEqual(result, ['c.tmp', 'd.tmp', 'e.tmp']);
 });
 
 test('glob - stream async iterator support', async t => {