Add sentenceCase option

packages/title-case/README.md

@@ -17,6 +17,15 @@ titleCase("string"); //=> "String"
 titleCase("follow step-by-step instructions"); //=> "Follow Step-by-Step Instructions"
 ```
 
+### Options
+
+- `locale?: string | string[]`
+- `sentenceCase?: boolean` Only capitalize the first word of each sentence (default: `false`)
+- `sentenceTerminators?: Set<string>` Set of characters to consider a new sentence under sentence case behavior (e.g. `.`, default: `SENTENCE_TERMINATORS`)
+- `smallWords?: Set<string>` Set of words to keep lower-case when `sentenceCase === false` (default: `SMALL_WORDS`)
+- `titleTerminators?: Set<string>` Set of characters to consider a new sentence under title case behavior (e.g. `:`, default: `TITLE_TERMINATORS`).
+- `wordSeparators?: Set<string>` Set of characters to consider a new word for capitalization, such as hyphenation (default: `WORD_SEPARATORS`).
+
 ## TypeScript and ESM
 
 This package is a [pure ESM package](https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c) and ships with TypeScript definitions. It cannot be `require`'d or used with CommonJS module resolution in TypeScript.

packages/title-case/src/index.spec.ts

@@ -1,11 +1,11 @@
 import { describe, it, expect } from "vitest";
 import { inspect } from "util";
-import { titleCase } from "./index.js";
+import { titleCase, Options } from "./index.js";
 
 /**
  * Based on https://github.com/gouch/to-title-case/blob/master/test/tests.json.
  */
-const TEST_CASES: [string, string][] = [
+const TEST_CASES: [string, string, Options?][] = [
   ["", ""],
   ["2019", "2019"],
   ["test", "Test"],
@@ -71,18 +71,30 @@ const TEST_CASES: [string, string][] = [
   ['"a quote." a test.', '"A Quote." A Test.'],
   ['"The U.N." a quote.', '"The U.N." A Quote.'],
   ['"The U.N.". a quote.', '"The U.N.". A Quote.'],
+  ['"The U.N.". a quote.', '"The U.N.". A quote.', { sentenceCase: true }],
   ['"go without"', '"Go Without"'],
   ["the iPhone: a quote", "The iPhone: A Quote"],
+  ["the iPhone: a quote", "The iPhone: a quote", { sentenceCase: true }],
   ["the U.N. and me", "The U.N. and Me"],
+  ["the U.N. and me", "The U.N. and me", { sentenceCase: true }],
+  ["the U.N. and me", "The U.N. And Me", { smallWords: new Set() }],
   ["start-and-end", "Start-and-End"],
   ["go-to-iPhone", "Go-to-iPhone"],
   ["Keep #tag", "Keep #tag"],
+  ['"Hello world", says John.', '"Hello World", Says John.'],
+  [
+    '"Hello world", says John.',
+    '"Hello world", says John.',
+    { sentenceCase: true },
+  ],
 ];
 
 describe("swap case", () => {
-  for (const [input, result] of TEST_CASES) {
-    it(`${inspect(input)} -> ${inspect(result)}`, () => {
-      expect(titleCase(input)).toEqual(result);
+  for (const [input, result, options] of TEST_CASES) {
+    it(`${inspect(input)} (${
+      options ? JSON.stringify(options) : "null"
+    }) -> ${inspect(result)}`, () => {
+      expect(titleCase(input, options)).toEqual(result);
     });
   }
 });

packages/title-case/src/index.ts

@@ -6,10 +6,10 @@ const IS_ACRONYM = /(?:\p{Lu}\.){2,}$/u;
 
 export const WORD_SEPARATORS = new Set(["—", "–", "-", "―", "/"]);
 
-export const SENTENCE_TERMINATORS = new Set([
-  ".",
-  "!",
-  "?",
+export const SENTENCE_TERMINATORS = new Set([".", "!", "?"]);
+
+export const TITLE_TERMINATORS = new Set([
+  ...SENTENCE_TERMINATORS,
   ":",
   '"',
   "'",
@@ -56,32 +56,36 @@ export const SMALL_WORDS = new Set([
 ]);
 
 export interface Options {
-  smallWords?: Set<string>;
+  locale?: string | string[];
+  sentenceCase?: boolean;
   sentenceTerminators?: Set<string>;
+  smallWords?: Set<string>;
+  titleTerminators?: Set<string>;
   wordSeparators?: Set<string>;
-  locale?: string | string[];
 }
 
 export function titleCase(
   input: string,
   options: Options | string[] | string = {},
 ) {
-  let result = "";
-  let m: RegExpExecArray | null;
-  let isNewSentence = true;
-
   const {
-    smallWords = SMALL_WORDS,
+    locale = undefined,
+    sentenceCase = false,
     sentenceTerminators = SENTENCE_TERMINATORS,
+    titleTerminators = TITLE_TERMINATORS,
+    smallWords = SMALL_WORDS,
     wordSeparators = WORD_SEPARATORS,
-    locale,
   } = typeof options === "string" || Array.isArray(options)
     ? { locale: options }
     : options;
 
+  const terminators = sentenceCase ? sentenceTerminators : titleTerminators;
+  let result = "";
+  let isNewSentence = true;
+
   // tslint:disable-next-line
-  while ((m = TOKENS.exec(input)) !== null) {
-    const { 1: token, 2: whiteSpace, index } = m;
+  for (const m of input.matchAll(TOKENS)) {
+    const { 1: token, 2: whiteSpace, index = 0 } = m;
 
     if (whiteSpace) {
       result += whiteSpace;
@@ -108,6 +112,11 @@ export function titleCase(
         if (isNewSentence) {
           isNewSentence = false;
         } else {
+          // Skip capitalizing all words if sentence case is enabled.
+          if (sentenceCase) {
+            continue;
+          }
+
           // Ignore small words except at beginning or end,
           // or previous token is a new sentence.
           if (
@@ -138,7 +147,7 @@ export function titleCase(
     }
 
     const lastChar = token.charAt(token.length - 1);
-    isNewSentence = sentenceTerminators.has(lastChar);
+    isNewSentence = terminators.has(lastChar);
   }
 
   return result;