Question

This code

var re = /(\w+)\s(\w+)/;
var str = "John Smith";
var newstr = str.replace(re, "$2, $1")

and this code

var re = /(.+)\s(.+)/;
var str = "John Smith";
var newstr = str.replace(re, "$2, $1")

does exactly the same thing.

Are there any key differences between . (dot) and \w metacharacters?

Answer 1

. matches any non-newline character.

\w matches a word character, i.e. is equivalent to [A-Za-z0-9_].

Using \w might seem the right way to go, but can go a bit wrong when dealing with names, as can be seen here:

var str = "Hans-Kristian Whistler";

var re = /(\w+)\s(\w+)/;
var newstr = str.replace(re, "$2, $1");
// result: Hans-Whistler, Kristian

var re = /(.+)\s(.+)/;
var newstr = str.replace(re, "$2, $1");
// result: Whistler, Hans-Kristian

See also:

• Character Classes on regular-expressions.info
• Dot on regular-expressions.info