JavaScript Regular Expression nothing to repeat

Question

I'm using the following JavaScript code to create a regular expression to match a UK mobile number:

new RegExp("(\+44|0)7\d{9}", 'g');

However, I get an error in the console log saying:

Uncaught SyntaxError: Invalid regular expression: /(?:+44|0)7d{9}/: Nothing to repeat

Similar questions on StackOverflow point to a missing escaped character, but mine seem to be fine.

I have also tried without the global flag.

Help would be greatly appreciated.

@AvinashRaj, that worked! Can you explain why this is the case? — Stefan Dunn, Mar 18 '15 at 11:23
within double quotes, escape all the backslashes one more time or otherwise it would treat backslash as an escape sequence. — Avinash Raj, Mar 18 '15 at 11:24
@AvinashRaj Within *all* string literals. JavaScript/ECMAScript makes no difference between single- and double-quoted strings, unlike e.g. PHP. And the point is that escape sequences *start* with a backslash both in string literals and `RegExp` initialisers (\\ is the escape sequence for the backslash in both literal types). The string literal is evaluated *before* the string value is passed to the `RegExp` constructor. As the other answer says, when there are no variable parts in the expression, use `RegExp` initialisers instead to avoid such errors and make the expression more readable. — PointedEars, Mar 18 '15 at 12:08

score 0 · Answer 1 · answered Mar 18 '15 at 11:43

0

You can create RegExp by using short method

var a = /(\+44|0)7\d{9}/g

Its must works good)

answered Mar 18 '15 at 11:43

Illia Moroz

1 Answers1