Question

I want to test a string’s format. This string should start with a + sign, then 2 digits, then a . sign, then 10 digits.

/^\+\d{2}\.\d{10}$/.test('+34.2398320186');

This way, it works (you can test it). But when I use RegExp, it says that the syntax has invalid quantifier error. What’s wrong?

Answer 1

You have to escape the \ with a second \\

new RegExp('^\\+\\d{2}\\.\\d{10}$'); // should work

I’ll add a recommendation from http://www.regular-expressions.info/javascript.html

I recommend that you do not use the RegExp constructor with a literal
string, because in literal strings, backslashes must be escaped.