Add TypeScript definition (#48)

Author: BendingBender

index.d.ts

@@ -0,0 +1,18 @@
+export interface Options {
+	/**
+	 * Uppercase the first character: `foo-bar` → `FooBar`.
+	 *
+	 * @default false
+	 */
+	readonly pascalCase?: boolean;
+}
+
+/**
+ * Convert a dash/dot/underscore/space separated string to camelCase or PascalCase: `foo-bar` → `fooBar`.
+ *
+ * @param input - String to convert to camel case.
+ */
+export default function camelcase(
+	input: string | ReadonlyArray<string>,
+	options?: Options
+): string;

index.js

@@ -29,7 +29,7 @@ const preserveCamelCase = string => {
 	return string;
 };
 
-module.exports = (input, options) => {
+const camelCase = (input, options) => {
 	if (!(typeof input === 'string' || Array.isArray(input))) {
 		throw new TypeError('Expected the input to be `string | string[]`');
 	}
@@ -73,3 +73,6 @@ module.exports = (input, options) => {
 
 	return postProcess(input);
 };
+
+module.exports = camelCase;
+module.exports.default = camelCase;

index.test-d.ts

@@ -0,0 +1,7 @@
+import {expectType} from 'tsd-check';
+import camelCase from '.';
+
+expectType<string>(camelCase('foo-bar'));
+expectType<string>(camelCase('Foo-Bar', {pascalCase: true}));
+expectType<string>(camelCase(['foo', 'bar']));
+expectType<string>(camelCase(['__foo__', '--bar'], {pascalCase: true}));

package.json

@@ -13,10 +13,11 @@
 		"node": ">=6"
 	},
 	"scripts": {
-		"test": "xo && ava"
+		"test": "xo && ava && tsd-check"
 	},
 	"files": [
-		"index.js"
+		"index.js",
+		"index.d.ts"
 	],
 	"keywords": [
 		"camelcase",
@@ -36,6 +37,7 @@
 	],
 	"devDependencies": {
 		"ava": "^1.2.1",
+		"tsd-check": "^0.3.0",
 		"xo": "^0.24.0"
 	}
 }