Adding modifiers to an existing regular expression

javascript regex modifier
Jinu Joseph Daniel picture Jinu Joseph Daniel · Feb 24, 2012 · Viewed 7.3k times · Source

I have a bunch of regular expressions like lower = /[a-z]/ Later in my program i need to use this as /[a-z]/g ie. i need to add the 'global' modifier later. So how to add a modifier to an existing regular expression?

Answer

epascarello picture epascarello · Feb 24, 2012

Use RegEx source and flags to separate the regular expression from the flags. Then create a new one with the string and set the needed flags.

var re = /^[a-z]*$/;
var re2 = new RegExp(re.source, re.flags + "i");

console.log( re.test("abc") )
console.log( re.test("ABC") )
console.log( re2.test("abc") )
console.log( re2.test("ABC") )

Related questions

How to validate an email address in JavaScript

Is there a regular expression to validate an email address in JavaScript?

Read More
Check whether a string matches a regex in JS

I want to use JavaScript (can be with jQuery) to do some client-side validation to check whether a string matches the regex: ^([a-z0-9]{5,})$ Ideally it would be an expression that returned true or false. I'm a JavaScript newbie, does …

Read More
How do you use a variable in a regular expression?

I would like to create a String.replaceAll() method in JavaScript and I'm thinking that using a regex would be most terse way to do it. However, I can't figure out how to pass a variable in to a regex. …

Read More