I was wondering if there is a way of testing if a regular expression inputted is valid in JavaScript.
Something like
if ( isValidRegexp($("#regexp")) {
...
}
I don't need a regex like this question Regexp that matches valid regexps
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I dont think I have ever seen invalid Regex, are there some characters that are not valid?musefan– musefan2013-04-26 07:43:13 +00:00Commented Apr 26, 2013 at 7:43
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Incorrectly nested brackets for example are considered to be invalid regex.martin– martin2013-04-26 07:48:08 +00:00Commented Apr 26, 2013 at 7:48
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@martin: I don't know what exactly musefan had in mind, but I'm certain that depending on its contents, a FOO is either a Regex or not-a-Regex, i.e. for me, improper nesting of brackets makes not-a-Regex :) Therefore we can argue about "ever seeing invalid Regex" :))quetzalcoatl– quetzalcoatl2013-04-26 09:04:38 +00:00Commented Apr 26, 2013 at 9:04
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2 Answers
You can create this function like this:
function isValidRE(str) {
var isValid=true;
try {
var re = new RegExp(str, "g");
} catch(err) {
isValid=false;
}
return isValid;
}
console.log(isValidRE("\d")); // true
console.log(isValidRE("(\d")); // false
Live Demo: http://ideone.com/9z2UKW
2 Comments
Archimedes Trajano
Chose this answer because it is a function, but what is the "g" for?
anubhava
g was for global, not really needed in this case and you can omit it.
OK, so it is pretty easy. You just create a new RegExp object and catch the error:
try{
var r = new RegExp("my regex string");
}
catch(e){
//regex is invalid
}
