Escape dot in a regex range

Question

Those two regex act the same way:

var str = "43gf\\..--.65";
console.log(str.replace(/[^\d.-]/g, ""));
console.log(str.replace(/[^\d\.-]/g, ""));

In the first regex I don't escape the dot(.) while in the second regex I do(\.).

What are the differences? Why is the result the same?

Answer 1

The dot operator . does not need to be escaped inside of a character class [].

Answer 2

Because the dot is inside character class (square brackets []).

Take a look at http://www.regular-expressions.info/reference.html, it says (under char class section):

Any character except ^-]\ add that character to the possible matches for the character class.

• gdoron: and the minus(-) needs to be escaped only if it's in the middle of the range?
• usoban: If you'd like to match hyphen, add it immediately after opening square bracket, e.g. [-A-Z]. Otherwise hyphen specifies range. It works in your case probably only because you're not specifing range in regex, but I'd suggest you follow the reference, in case you'll be adding range later.
• Code Jockey: or immediately before the closing bracket, or you could escape it with a slash

Answer 3

If you using JavaScript to test your Regex, try \\. instead of \..

It acts on the same way because JS remove first backslash.

• Mārtiņš Radiņš: This one saved me today. I couldn't figure out why the expression wouldn't work. Thanks

Answer 4

On regular-expressions.info, it is stated:

Remember that the dot is not a metacharacter inside a character class, so we do not need to escape it with a backslash.

So I guess the escaping of it is unnecessary...