Javascript regular expression character set limit

Question

I want to validate user's input and i use the following (which works fine) as regex.

 pattern = /^[a-zA-Z0-9 .,!?;-]+$/;

But when i try with all the characters i want, which is this.

pattern = /^[a-zA-Z0-9 .,!?;-:()@'+=/]+$/;

It doesn't work and I dont know why. Also, I would appreciate it a lot if you explained to me what's the difference when I add the ^ and the +$. Also i have tried using \s instead of space, and it still doesn't work(I prefer just space because i want to restrict line change).

Please go ahead and do some reading on the basics of RegExp: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions — Derek 朕會功夫, Sep 04 '16 at 18:49
Slash inside brackets must be escaped. `/^[a-zA-Z0-9 .,!?;-:()@'+=\/]+$/;` — Alex Kudryashev, Sep 04 '16 at 18:52
I tried `/^[a-zA-Z0-9 .,!?;-:()@'+=\/]+$/` but it didn't work — NiXt, Sep 04 '16 at 19:02

Makyen · Accepted Answer · 2016-09-04T19:37:45.247

The "hyphen-minus" character, -, has special meaning within a character set (a set of characters between [ and ]). It, -, defines a range of characters. Most of the time in a character set that you want the - to represent itself, you need to use \- to escape its special meaning. In your use, - needs to be escaped \- when used between ; and :.

Working:

pattern = /^[a-zA-Z0-9 .,!?;\-:()@'+=/]+$/;

If you actually want the range of characters between : and ;, then you need to specify the one that has a lower character code (Ascii code chart, or Unicode) first. In this case, that means :-; as : comes before ;:

Show :-; range is valid:

pattern = /^[a-zA-Z0-9 .,!?:-;()@'+=/]+$/;

The same error would be generated if you were to try to specify a range such as z-a.

Show same error with range of z-a:

pattern = /^[z-aA-Z0-9 .,!?:-;()@'+=/]+$/;

The - does not take on its special meaning if it is the first or last character in the character set.

Note: In some regular expression implementations, the - does have its special meaning if you try to use it as the last character in the character set. You are better off just being in the habit of escaping it with \-.

Using - as first or last character in character set:

pattern = /^[-a-zA-Z0-9 .,!?;:()@'+=/]+$/;
pattern = /^[a-zA-Z0-9 .,!?;:()@'+=/-]+$/;

Original code with error:

pattern = /^[a-zA-Z0-9 .,!?;-:()@'+=/]+$/;

Javascript regular expression character set limit

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