📘str.match()

str.match() 的回傳值有三種模式：

-----------------------------------------------
   matched   /g    return value    capture groups
-----------------------------------------------
1. ✅ 	     ✅     all matches	   ❌
2. ✅        ❌     first match     ✅
3. ❌               null
-----------------------------------------------

global mode (with /g set): return array of all matches (without info about capturing groups)
non-global mode (with /g not set): return array of first match (including additional info about capturing groups)
no match: return null.

replit

//                       first match ↴
//             0         1         2         3         4
//      index: 01234567890123456789012345678901234567890
//                                   ╭── first match ──╮
const found = 'For more information, see Chapter 3.4.5.1'.match(
//                                       ╰─── group ───╯
    /see (chapter \d+(\.\d)*)/i     // ignore case, non-global
);

// ⭐️ three modes of str.match(regex) method's return value

log(found);
// ⭐️ 2. non-gloabl mode:
//   (return array of informations about first match)
// [
//   'see Chapter 3.4.5.1',         // whole match
//   'Chapter 3.4.5.1',             // first capture group ⭐️
//   '.1',                          // last value captured by '(\.\d)'
//   index: 22,                     // index of the whole match
//   input: 'For more information, see Chapter 3.4.5.1',    // original string
//   groups: undefined              // object of named capturing groups
// ]

let str = "We will, we will rock you";

// ⭐️ 1. global mode:
//   (return array of all matches, no capturing groups)
str.match(/we/gi),      // [ 'We', 'we' ]

// ⭐️ 3. no match:
//    (return null)
str.match(/they/),      // null ⭐️

A1NotationToRowColumn() - "AA3" to [ "AA", "3" ].

Previousstr.kebabToCamelCase()Nextsplit into course names

Last updated 2 years ago

----------------------------------------------- matched /g return value capture groups ----------------------------------------------- 1. ✅ ✅ all matches ❌ 2. ✅ ❌ first match ✅ 3. ❌ null -----------------------------------------------

// first match ↴ // 0 1 2 3 4 // index: 01234567890123456789012345678901234567890 // ╭── first match ──╮ const found = 'For more information, see Chapter 3.4.5.1'.match( // ╰─── group ───╯ /see (chapter \d+(\.\d)*)/i // ignore case, non-global ); // ⭐️ three modes of str.match(regex) method's return value log(found); // ⭐️ 2. non-gloabl mode: // (return array of informations about first match) // [ // 'see Chapter 3.4.5.1', // whole match // 'Chapter 3.4.5.1', // first capture group ⭐️ // '.1', // last value captured by '(\.\d)' // index: 22, // index of the whole match // input: 'For more information, see Chapter 3.4.5.1', // original string // groups: undefined // object of named capturing groups // ] let str = "We will, we will rock you"; // ⭐️ 1. global mode: // (return array of all matches, no capturing groups) str.match(/we/gi), // [ 'We', 'we' ] // ⭐️ 3. no match: // (return null) str.match(/they/), // null ⭐️