From e0ded850228ca4038b5b088a919fef6d35d258cb Mon Sep 17 00:00:00 2001
From: "Rong Sen Ng (motss)" <wes.ngrongsen@gmail.com>
Date: Thu, 2 May 2019 20:54:39 +0800
Subject: [PATCH] =?UTF-8?q?=E2=8F=AA=20src:=20Revert=20change=20to=20use?=
 =?UTF-8?q?=20native=20String.prototype.normalize?=
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---
 src/index.ts           | 32 ++++++++++-------------
 src/test/index.spec.ts | 58 ++++++++----------------------------------
 2 files changed, 25 insertions(+), 65 deletions(-)

diff --git a/src/index.ts b/src/index.ts
index 13b44d5..718f345 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -111,30 +111,26 @@ export const diacritics: Diacritics[] = [
 ];
 // tslint:enable:max-line-length
 
-function nativeStringNormalize(s: string) {
-  /**
-   * NOTE: Normalizing accents/ diacritics in ES6.
-   * See https://bit.ly/2Cncgor for more info.
-   */
-  return s.normalize('NFD').replace(/[\u0300-\u036f]/g, '');
-}
-
-function stringNormalize(s: string) {
-  const normalized = diacritics.filter(n => n.diacritics.test(s));
-  return !normalized.length ? s : normalized[0].letter;
-}
-
 export function normalizeSync(input?: string | null) {
   if ('string' !== typeof(input)) {
     throw new TypeError(`Expected 'input' to be of type string, but received '${input}'`);
   }
 
-  const replaceDiacritics =
-    'function' === typeof(''.normalize) && 'aeo' === nativeStringNormalize('áèö') ?
-      (s: string) => nativeStringNormalize(s) : (s: string) => stringNormalize(s);
-
+  /**
+   * NOTE(motss): Due to the fact that this module should do what we expect it to be - normalize
+   * accents/ diacritics. However, some characters are not accented such as those from
+   * [Latin-1 Supplement](https://bit.ly/2vz1l7m). Also see a relevant
+   * [GH issue](https://bit.ly/2JbAmH0).
+   *
+   * Hence, to match the mental module of the users, `String.prototype.normalize` should not be used
+   * as such.
+   */
   return !input.length ?
-    input : input.replace(/(\S)/g, (_, p: string) => replaceDiacritics(p));
+    input :
+    input.replace(/(\S)/g, (_, s: string) => {
+      const normalized = diacritics.find(n => n.diacritics.test(s));
+      return null == normalized ? s : normalized.letter;
+    });
 }
 
 export async function normalize(input?: string | null) {
diff --git a/src/test/index.spec.ts b/src/test/index.spec.ts
index 3d04006..7dd5bb6 100644
--- a/src/test/index.spec.ts
+++ b/src/test/index.spec.ts
@@ -11,19 +11,6 @@ describe('normalize-diacritics', () => {
       }
     });
 
-    it(`throws error in 'replaceDiacritics'`, async () => {
-      const cachedFn = String.prototype.normalize;
-      String.prototype.normalize = () => { throw new Error('String#normalize is broken'); };
-
-      try {
-        await normalize('Réunion');
-      } catch (e) {
-        expect(e).toStrictEqual(new Error('String#normalize is broken'));
-      } finally {
-        String.prototype.normalize = cachedFn;
-      }
-    });
-
     it(`throws when 'input' is 'undefined'`, async () => {
       try {
         await normalize();
@@ -36,13 +23,17 @@ describe('normalize-diacritics', () => {
   });
 
   describe('ok', () => {
-    it('normalizes strings', async () => {
+    it(`skips normalization for empty character`, async () => {
+      expect(await normalize('')).toStrictEqual('');
+    });
+
+    it('normalizes accented characters', async () => {
       try {
         const strs = [
           'Åland Islands',
           'Saint Barthélemy',
           'Cocos (Keeling) Islands',
-          'Côte d\'Ivoire',
+          `Côte d'Ivoire`,
           'Curaçao',
           'Réunion',
         ];
@@ -50,7 +41,7 @@ describe('normalize-diacritics', () => {
         expect(await normalize(strs[0])).toStrictEqual('Aland Islands');
         expect(await normalize(strs[1])).toStrictEqual('Saint Barthelemy');
         expect(await normalize(strs[2])).toStrictEqual('Cocos (Keeling) Islands');
-        expect(await normalize(strs[3])).toStrictEqual('Cote d\'Ivoire');
+        expect(await normalize(strs[3])).toStrictEqual(`Cote d'Ivoire`);
         expect(await normalize(strs[4])).toStrictEqual('Curacao');
         expect(await normalize(strs[5])).toStrictEqual('Reunion');
       } catch (e) {
@@ -58,7 +49,7 @@ describe('normalize-diacritics', () => {
       }
     });
 
-    it('normalizes string without using native function', async () => {
+    it('normalizes accented characters without using native function', async () => {
       const cachedFn = String.prototype.normalize;
       String.prototype.normalize = null!;
 
@@ -71,36 +62,9 @@ describe('normalize-diacritics', () => {
       }
     });
 
-    it('returns original character when no match found', async () => {
-      const cachedFilter = Array.prototype.filter;
-      const cachedFn = String.prototype.normalize;
-      Array.prototype.filter = () => [];
-      String.prototype.normalize = null!;
-
-      try {
-        expect(await normalize('Réunion')).toStrictEqual('Réunion');
-      } catch (e) {
-        throw e;
-      } finally {
-        Array.prototype.filter = cachedFilter;
-        String.prototype.normalize = cachedFn;
-      }
-    });
-
-    it('normalizes single-character string', async () => {
-      try {
-        expect(await normalize('ô')).toStrictEqual('o');
-      } catch (e) {
-        throw e;
-      }
-    });
-
-    it('returns empty string untouched', async () => {
-      try {
-        expect(await normalize('')).toStrictEqual('');
-      } catch (e) {
-        throw e;
-      }
+    it(`normalizes non-accented characters (Latin-1 Supplement)`, async () => {
+      expect(await normalize('tromsø')).toStrictEqual('tromso');
+      expect(await normalize('\u00d8')).toStrictEqual('O');
     });
 
   });