🔰using regex

🚧 under construction

JS ⟩ value ⟩ object ⟩ regex ⟩ using regex

Regular expressions are used

• with re.test(), re.exec()

• with str.match(), str.replace(), str.search(), str.split().

🧨 雷區

when using str.matchAll(regex), the regex must have the global (g) flag set, or a TypeError is thrown❗

⭐️ 重點

Method	Return Value or Side Effect
re.exec()	array of information or null.
re.test()	true or false.
str.match()	array containing all of the matches (including capturing groups), or null.
str.matchAll()	iterator containing all of the matches (including capturing groups).
str.search()	index of the match, or -1.
str.replace()	replaces the matched substring with a replacement substring.
str.replaceAll()	replaces the matched substrings with a replacement substring.
str.split()	break a string into an array of substrings.

💈範例

/abc/.test("xxabcde"),    // true
/abc/.test("xxabxde"),    // false

💈範例：

• JS-style numbers

👥 相關

• str.indexOf() can search for substrings too.

• str.matchAll()

• str.replace()

• replace pattern

📗 參考

• Eloquent JavaScript ⟩ Regular Expressions ⟩ Testing for Matches

📘 手冊

• regex.test() - test if a match exists.

• regex.exec() - use str.matchAll() instead.

• str.search() - index of first match, -1 otherwise.

• str.matchAll() - contents of matches.