Regex working in application but not in Regex101

Question

I want to use the below regex in my JS that is already working on a "phone number" form field in my company's application.

When I attempt to put it into Regex101's playground and type in 777-777-7777 I cannot get a match. It makes no sense. Anyone know what the issue can be? I am just trying to gain a better understanding of regular expressions as a junior developer.

[2-9]\\d{2}(-){0,1}[2-9]\\d{2}(-){0,1}\\d{4}$

If you read regex 101's description of your regex (over on the right side), you would see that it says *\\ matches the character \ literally*. By the way, `{0,1}` can be written as `?`. Also, don't you want to anchor this at the beginning with `^`? — , Jan 26 '17 at 17:41

score 0 · Accepted Answer · answered Jan 26 '17 at 17:05

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In Javascript regex, you must escape the backslashes (\), so your regex looks like [2-9]\\d{2}(-){0,1}[2-9]\\d{2}(-){0,1}\\d{4}$.

But for Regex101, you must unescape them, so your regex is [2-9]\d{2}(-){0,1}[2-9]\d{2}(-){0,1}\d{4}$

As a sidenote: do you really mean to capture the -?

answered Jan 26 '17 at 17:05

Bruno Ferreira

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You only need to escape it, if the regex is defined as a string in JavaScript. JavaScript has a regex notation, where you don't need to escape it: `var regex = /regex/;` – ssc-hrep3 Jan 26 '17 at 17:08
@ssc-hrep3 yes, forgot to mention that. considering that the OP escaped the backslashes, it was implicit that he was using string. – Bruno Ferreira Jan 26 '17 at 17:10
I sure was! pattern: { message: "Invalid", params: "[2-9]\\d{2}(-){0,1}[2-9]\\d{2}(-){0,1}\\d{4}$"} }); – Dean Friedland Jan 26 '17 at 17:21
Oh, and @BrunoFerreira, is there no reason to capture "-" ? – Dean Friedland Jan 26 '17 at 17:23
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it depends on your following code. if you are using only for validation of a string format, then no – Bruno Ferreira Jan 26 '17 at 17:25

Regex working in application but not in Regex101

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