Groups in JavaScript

(x)         Capturing group
(?:x)       Non-capturing group
(?<name>x)  Named capturing group
\1, \2      Backreference to group 1, 2
\k<name>    Backreference to named group

// Examples
const match = "John Smith".match(/(\w+) (\w+)/)
// match[0]: "John Smith" (full match)
// match[1]: "John" (group 1)
// match[2]: "Smith" (group 2)

// Named groups
const regex = /(?<year>\d{4})-(?<month>\d{2})-(?<day>\d{2})/
const result = "2024-03-15".match(regex)
// result.groups.year: "2024"
// result.groups.month: "03"
// result.groups.day: "15"

// Non-capturing group (for grouping only)
/(?:https?):\/\//.test("https://")  // true
// Won't create a capture group

// Backreferences
/(\w+) \1/.test("hello hello")      // true (repeated word)
/(['"])(.*?)\1/.test('"text"')      // true (matching quotes)