Question
I just want to create a regular expression out of any possible string.
var usersString = "Hello?!*`~World()[]";
var expression = new RegExp(RegExp.escape(usersString))
var matches = "Hello".match(expression);
Is there a built-in method for that? If not, what do people use? Ruby has
RegExp.escape. I
don't feel like I'd need to write my own, there have got to be something
standard out there.
Answer
The function linked in another answer is insufficient. It fails to escape ^
or $ (start and end of string), or -, which in a character group is used
for ranges.
Use this function:
function escapeRegex(string) {
return string.replace(/[/\-\\^$*+?.()|[\]{}]/g, '\\$&');
}
While it may seem unnecessary at first glance, escaping - (as well as ^)
makes the function suitable for escaping characters to be inserted into a
character class as well as the body of the regex.
Escaping / makes the function suitable for escaping characters to be used in
a JavaScript regex literal for later evaluation.
As there is no downside to escaping either of them, it makes sense to escape to cover wider use cases.
And yes, it is a disappointing failing that this is not part of standard JavaScript.
