Passing regex modifier options to RegExp object

Question

I am trying to create something similar to this:

var regexp_loc = /e/i;

except I want the regexp to be dependent on a string, so I tried to

Answer 1

You should also remember to watch out for escape characters within a string...

For example if you wished to detect for a single number \d{1} and you did this...

var pattern = "\d{1}";
var re = new RegExp(pattern);

re.exec("1"); // fail! :(

that would fail as the initial \ is an escape character, you would need to "escape the escape", like so...

var pattern = "\\d{1}" // <-- spot the extra '\'
var re = new RegExp(pattern);

re.exec("1"); // success! :D