let hello = " Hello, World! ";
let wsRegex = /^(\s+)(.+[^\s])(\s+)$/; // Change this line
let result = hello.replace(wsRegex, ‘$2’); // Change this line
can somoene tell me what’s the meaning of the $2 thing and how it works please ??
let hello = " Hello, World! ";
let wsRegex = /^(\s+)(.+[^\s])(\s+)$/; // Change this line
let result = hello.replace(wsRegex, ‘$2’); // Change this line
can somoene tell me what’s the meaning of the $2 thing and how it works please ??
$2
is the second captured group
In regex, wrapping patterns in brackets captures them as groups for reuse, kinda like assigning to a variable.
The first captured bracket (\s+)
is assigned to \1
within the same pattern and $1
outside the pattern, second captured group (.+[^\s])
is assigned to \2
and $2
and so on…
For example, /^(\s+)(.+[^\s])(\s+)$/;
can also be written as /^(\s+)(.+[^\s])\1$/;
reusing the first capture group.
If you want to use brackets within patterns without capturing, you can add ?:
to ignore the group, just like this (?:\s+)
means match it but don’t assign any variable.
hello.replace(wsRegex, ‘$2’)
means replace all the match with the second capture group.
Since the first and second capture groups are whitespaces
the result will be equal to replace . so .
with .so.
ThankYou that was very helpful