javascript - How to check if the input string is a valid Regular expression?

Question

How do you check, in JavaScript, if a string is a proper regular expression that will compile?

For example, when you execute the following javascript, it produces an error.

var regex = new RegExp('abc ([a-z]+) ([a-z]+))');
// produces:
// Uncaught SyntaxError: Invalid regular expression: /abc ([a-z]+) ([a-z]+))/: Unmatched ')'

How does one determine if a string will be a valid regex or not?

Answer 1

You can use try/catch and the RegExp constructor:

var isValid = true;
try {
    new RegExp("the_regex_to_test_goes_here");
} catch(e) {
    isValid = false;
}

if(!isValid) alert("Invalid regular expression");