Question

I have this string : "xvvv 123y"

I wanted to test the replace command

So I created :

"xvvv 123y".match(/(v+).+?([0-9]+)/)

result :

["vvv 123", "vvv", "123"] //let’s remember this array.

All Ok.

• Now say I want to replace the matching text to group $1 ==>

  "xvvv 123y".replace(/(v+).+?([0-9]+)/,'$1')

  result : "xvvvy" Ok.

• Now say I want to replace the matching text to group $2 ==>

  "xvvv 123y".replace(/(v+).+?([0-9]+)/,'$2')

  result : "x123y" Ok.

• Now say I want to replace the matching text to group $0 ==>

                  ["vvv   123", "vvv", "123"]
                         ^ 
                         |
  I mean to -------------
  

  "xvvv 123y".replace(/(v+).+?([0-9]+)/,'$0')

  result : "x$0y" OOPSS ?

Why it wont allow me replace the matching text to the first indexe group ?

edit

And why it returns the first element if I cant access it ?

Answer 1

The first element in the return value of match is the string which represents the full match. This value is accessible through $&:

"xvvv 123y".replace(/(v+).+?([0-9]+)/, '$&');
// Result: ""xvvv 123y"