Return undefined instead of null when the path cannot be found

index.d.ts

@@ -13,8 +13,8 @@ declare const findUp: {
 	/**
 	Find a file or directory by walking up parent directories.
 
-	@param filename - Filename of the file or an array of files to find.
-	@returns Either the first filepath found (by respecting the order of `filename`s) or `null`.
+	@param name - Name of the file or directory to find. Can be multiple.
+	@returns The first path found (by respecting the order of `name`s) or `undefined` if none could be found.
 
 	@example
 	```
@@ -39,17 +39,15 @@ declare const findUp: {
 	})();
 	```
 	*/
-	(filename: string | string[], options?: findUp.Options): Promise<
-		string | null
-	>;
+	(name: string | string[], options?: findUp.Options): Promise<string | undefined>;
 
 	/**
 	Synchronously find a file or directory by walking up parent directories.
 
-	@param filename - Filename of the file or an array of files to find.
-	@returns Either the first filepath found (by respecting the order of `filename`s) or `null`.
+	@param name - Name of the file or directory to find. Can be multiple.
+	@returns The first path found (by respecting the order of `names`s) or `undefined` if none could be found.
 	*/
-	sync(filename: string | string[], options?: findUp.Options): string | null;
+	sync(name: string | string[], options?: findUp.Options): string | undefined;
 };
 
 export = findUp;

index.js

@@ -2,19 +2,19 @@
 const path = require('path');
 const locatePath = require('locate-path');
 
-module.exports = (filename, options = {}) => {
+module.exports = (name, options = {}) => {
 	const startDirectory = path.resolve(options.cwd || '');
 	const {root} = path.parse(startDirectory);
 
-	const filenames = [].concat(filename);
+	const paths = [].concat(name);
 
 	return new Promise(resolve => {
 		(function find(directory) {
-			locatePath(filenames, {cwd: directory}).then(file => {
-				if (file) {
-					resolve(path.join(directory, file));
+			locatePath(paths, {cwd: directory}).then(foundPath => {
+				if (foundPath) {
+					resolve(path.join(directory, foundPath));
 				} else if (directory === root) {
-					resolve(null);
+					resolve();
 				} else {
 					find(path.dirname(directory));
 				}
@@ -23,22 +23,22 @@ module.exports = (filename, options = {}) => {
 	});
 };
 
-module.exports.sync = (filename, options = {}) => {
+module.exports.sync = (name, options = {}) => {
 	let directory = path.resolve(options.cwd || '');
 	const {root} = path.parse(directory);
 
-	const filenames = [].concat(filename);
+	const paths = [].concat(name);
 
 	// eslint-disable-next-line no-constant-condition
 	while (true) {
-		const file = locatePath.sync(filenames, {cwd: directory});
+		const foundPath = locatePath.sync(paths, {cwd: directory});
 
-		if (file) {
-			return path.join(directory, file);
+		if (foundPath) {
+			return path.join(directory, foundPath);
 		}
 
 		if (directory === root) {
-			return null;
+			return;
 		}
 
 		directory = path.dirname(directory);

index.test-d.ts

@@ -1,16 +1,12 @@
 import {expectType} from 'tsd';
 import findUp = require('.');
 
-expectType<Promise<string | null>>(findUp('unicorn.png'));
-expectType<Promise<string | null>>(findUp('unicorn.png', {cwd: ''}));
-expectType<Promise<string | null>>(findUp(['rainbow.png', 'unicorn.png']));
-expectType<Promise<string | null>>(
-	findUp(['rainbow.png', 'unicorn.png'], {cwd: ''})
-);
+expectType<Promise<string | undefined>>(findUp('unicorn.png'));
+expectType<Promise<string | undefined>>(findUp('unicorn.png', {cwd: ''}));
+expectType<Promise<string | undefined>>(findUp(['rainbow.png', 'unicorn.png']));
+expectType<Promise<string | undefined>>(findUp(['rainbow.png', 'unicorn.png'], {cwd: ''}));
 
-expectType<string | null>(findUp.sync('unicorn.png'));
-expectType<string | null>(findUp.sync('unicorn.png', {cwd: ''}));
-expectType<string | null>(findUp.sync(['rainbow.png', 'unicorn.png']));
-expectType<string | null>(
-	findUp.sync(['rainbow.png', 'unicorn.png'], {cwd: ''})
-);
+expectType<string | undefined>(findUp.sync('unicorn.png'));
+expectType<string | undefined>(findUp.sync('unicorn.png', {cwd: ''}));
+expectType<string | undefined>(findUp.sync(['rainbow.png', 'unicorn.png']));
+expectType<string | undefined>(findUp.sync(['rainbow.png', 'unicorn.png'], {cwd: ''}));

readme.md

@@ -53,31 +53,31 @@ const findUp = require('find-up');
 
 ## API
 
-### findUp(filename, [options])
+### findUp(name, [options])
 
-Returns a `Promise` for either the filepath or `null` if it couldn't be found.
+Returns a `Promise` for either the path or `undefined` if it couldn't be found.
 
-### findUp([filenameA, filenameB], [options])
+### findUp([nameA, nameB], [options])
 
-Returns a `Promise` for either the first filepath found (by respecting the order) or `null` if none could be found.
+Returns a `Promise` for either the first path found (by respecting the order) or `undefined` if none could be found.
 
-### findUp.sync(filename, [options])
+### findUp.sync(name, [options])
 
-Returns a filepath or `null`.
+Returns a path or `undefined` if it couldn't be found.
 
-### findUp.sync([filenameA, filenameB], [options])
+### findUp.sync([nameA, nameB], [options])
 
-Returns the first filepath found (by respecting the order) or `null`.
+Returns the first path found (by respecting the order) or `undefined` if none could be found.
 
-#### filename
+#### name
 
 Type: `string`
 
-Filename of the file to find.
+Name of the file or directory to find.
 
 #### options
 
-Type: `Object`
+Type: `object`
 
 ##### cwd