💩 src: Minor fixes

Fixed typings in source.

Added new test for normalizing empty string.

Minor update in docs.

README.md

@@ -48,7 +48,7 @@ import { normalize } from 'https://denopkg.com/motss/normalize-diacritics@v1.0.0
 
 ### normalize([input])
 
-- `input` <[?string][string-mdn-url]> Input string that contains accents/ diacritics.
+- `input` <[?string][string-mdn-url]> Optional input string that contains accents/ diacritics.
 - returns: <[Promise][promise-mdn-url]<[string][string-mdn-url]>> Promise which resolves with normalized input string.
 
 This method normalizes any accents/ diacritics found in a given input string and output a normalized string as a result.

index.ts

@@ -116,12 +116,12 @@ function replaceDiacritics(inputChar: string) {
   return Array.isArray(normalized) && normalized.length > 0 ? normalized[0].letter : inputChar;
 }
 
-export function normalizeSync(input: string) {
+export function normalizeSync(input?: string) {
   if (typeof input !== 'string') {
     throw new TypeError(`Expected 'input' to be of type string, but received '${input}'`);
   }
 
-  return !input.length ? input : input.replace(/(\S)/g, (_, p) => replaceDiacritics(p));
+  return !input.length ? input : input.replace(/(\S)/g, (_, p: string) => replaceDiacritics(p));
 }
 
 export async function normalize(input?: string) {

test/index.spec.ts

@@ -44,7 +44,7 @@ async function normalizesStrings() {
 
 async function normalizesStringsWithoutUsingNativeFunction() {
   const cachedFn = String.prototype.normalize;
-  String.prototype.normalize = null;
+  String.prototype.normalize = null!;
 
   try {
     assertEqual(await normalize('Réunion'), 'Reunion');
@@ -59,7 +59,7 @@ async function returnsOriginalCharacterWhenNoMatchFound() {
   const cachedFilter = Array.prototype.filter;
   const cachedFn = String.prototype.normalize;
   Array.prototype.filter = () => [];
-  String.prototype.normalize = null;
+  String.prototype.normalize = null!;
 
   try {
     assertEqual(await normalize('Réunion'), 'Réunion');
@@ -75,12 +75,17 @@ async function normalizeSingleCharacter() {
   assertEqual(await normalize('ô'), 'o');
 }
 
+async function returnsEmptyStringUnTouched() {
+  assertEqual(await normalize(''), '');
+}
+
 Promise.all([
   throwsWhenInvalidInput,
   throwsWhenInputIsUndefined,
   normalizesStringsWithoutUsingNativeFunction,
   returnsOriginalCharacterWhenNoMatchFound,
   normalizeSingleCharacter,
+  returnsEmptyStringUnTouched,
 ].map(n => test(n)));
 
 /**