🔰replace pattern

JS ⟩ value ⟩ object ⟩ regex ⟩ pattern ⟩ replace pattern

$n	// Insert the contents of unnamed capture #n
${foo}	// Insert the contents of named capture “foo”
$0	// Insert all text matched in the regex (automatic unnamed capture)
$`      // (backtick)	Insert text before $0
$'      // (single-quote)	Insert text after $0
$_	// Insert the entire original filename (same as $`$0$')
$#	// Insert a number sequence (see Numbering)
$$	// Insert an actual $ character (therefore, $$# to insert actual $#)
// For unnamed captures, use ${n} if the following character is an actual digit
// Any text other than the variables above will be replaced as-is.

👉 str.replace() ⟩ replacer function for more examples.

💈範例

// global vs non-global replace
"Borobudur".replace(/[ou]/ , "a")    // Barobudur
"Borobudur".replace(/[ou]/g, "a")   // Barabadar

// replace pattern
const names = "Liskov, Barbara\nMcCarthy, John\nWadler, Philip"
names.replace(/(\w+), (\w+)/g, "$2 $1")    // unnamed capture $n
// Barbara Liskov
// John McCarthy
// Philip Wadler

// quoting style: single (') -> double (")
let text = "'I'm the cook,' he said, 'it's my job.'";
text.replace(/(^|\W)'|'(\W|$)/g, '$1"$2'));
//            ╰─1──╯   ╰─2──╯ 
//  ⭐️ Groups that are not matched will be replaced by nothing.
// → "I'm the cook," he said, "it's my job."

📗 參考

• Regular Expression Quick Reference

• Eloquent JS ⟩ Regular Expressions ⟩

  • Sets of Characters

  • The replace method

  • Quoting Style