I have a following regex expression in javascript

var reg = new RegExp("^[(]?[2-9]\d{2}[)]?[\-. :]?[2-9]\d{2}[\-. :]?\d{4}$");
return this.optional(element) || (reg.test(value));

in my code reg.test(value) return false even on correct values: for instance 222 222 2222 or 222-222-2222. All regex testers(especially this one, which calls the same methods) show that regex matches the expression. What can be the problem?

I have a following regex expression in javascript

var reg = new RegExp("^[(]?[2-9]\d{2}[)]?[\-. :]?[2-9]\d{2}[\-. :]?\d{4}$");
return this.optional(element) || (reg.test(value));

in my code reg.test(value) return false even on correct values: for instance 222 222 2222 or 222-222-2222. All regex testers(especially this one, which calls the same methods) show that regex matches the expression. What can be the problem?

• javascript
• regex
• validation

4 Answers 4

Try this:

var reg = /^[(]?[2-9]\d{2}[)]?[\-. :]?[2-9]\d{2}[\-. :]?\d{4}$/;
return this.optional(element) || (reg.test(value));

Or also:

var reg = new RegExp("^[(]?[2-9]\\d{2}[)]?[\\-. :]?[2-9]\\d{2}[\\-. :]?\\d{4}$");
return this.optional(element) || (reg.test(value));

The \s are being swallowed by the string literal.

You should use a regex literal instead:

var reg = /^[(]?[2-9]\d{2}[)]?[\-. :]?[2-9]\d{2}[\-. :]?\d{4}$/;

I see one potential cause of troubles: if you're creating a new Regular Expression using the RegExp function, you'll have to escape backslashes twice - once for the JavaScript engine, and once for the RegEx engine.

You can test if this is causing the troubles by doing

var reg = /^[(]?[2-9]\d{2}[)]?[\-. :]?[2-9]\d{2}[\-. :]?\d{4}$/;

You are taking the regex in as a string so all of the occurrences of \d should be \\d because when the regex string is sent to the interpreter the \d character is not interpreted as a \ and a d but just a d adding the extra slash escapes the other slash so the \\d is interpreted as a \ and a d. Also I suggest one other change, the [(] should be replaced with \\( because the character class only contains one character and therefore has no point.