Finding Plus Sign in Regular Expression

Question

var string = 'abcd+1'; var pattern = 'd+1' var reg = new RegExp(pattern,''); alert(string.search(reg)); 

I found out last night that if you try and find a plus sign in a string of text with a Javascript regular expression, it fails. It will not find that pattern, even though it exists in that string. This has to be because of a special character. What's the best way to find a plus sign in a piece of text? Also, what other characters will this fail on?

Answer 1

Plus is a special character in regular expressions, so to express the character as data you must escape it by prefixing it with \.

var reg = /d\+1/; 

Answer 2

\-\.\/\[\]\\ **always** need escaping \*\+\?\)\{\}\| need escaping when **not** in a character class- [a-z*+{}()?] 

But if you are unsure, it does no harm to include the escape before a non-word character you are trying to match.

A digit or letter is a word character, escaping a digit refers to a previous match, escaping a letter can match an unprintable character, like a newline (\n), tab (\t) or word boundary (\b), or a a set of characters, like any word-character (\w), any non-word character (\W).

Don't escape a letter or digit unless you mean it.