Javascript + Regex = Nothing to repeat error?

Question

I'm new to Regex and I'm trying to work it into one of my new projects to see if I can learn it and add it to my repitoire of skills. However, I'm hitting a roadblock here.

I'm trying to see if the user's input has illegal characters in it by using the .search function as so:

if (name.search("[\[\]\?\*\+\|\{\}\\\(\)\@\.\n\r]") != -1) {
    ...
}

However, when I try to execute the function this line is contained it, it throws the following error for that specific line:

Uncaught SyntaxError: Invalid regular expression: /[[]?*+|{}\()@.

]/: Nothing to repeat

I can't for the life of me see what's wrong with my code. Can anyone point me in the right direction?

Answer 1

You need to double the backslashes used to escape the regular expression special characters. However, as @Bohemian points out, most of those backslashes aren't needed. Unfortunately, his answer suffers from the same problem as yours. What you actually want is:

The backslash is being interpreted by the code that reads the string, rather than passed to the regular expression parser. You want:

"[\\[\\]?*+|{}\\\\()@.\n\r]"

Note the quadrupled backslash. That is definitely needed. The string passed to the regular expression compiler is then identical to @Bohemian's string, and works correctly.

Answer 2

Building off of @Bohemian, I think the easiest approach would be to just use a regex literal, e.g.:

if (name.search(/[\[\]?*+|{}\\()@.\n\r]/) != -1) {
    // ... stuff ...
}

Regex literals are nice because you don't have to escape the escape character, and some IDE's will highlight invalid regex (very helpful for me as I constantly screw them up).