Regular expressions: character class vs OR operator

JavaScript
1

The challenge Regular Expressions: Match Single Character with Multiple Possibilities made me wonder: is there any difference between using the alteration, or OR operator, between each letter of aeiou and putting aeiou in a character class as called for in the challenge? I’m pretty sure the following would produce the same result (though it doesn’t pass that challenge because a character class is not used) but want to be sure.

let quoteSample = "Beware of bugs in the above code; I have only proved it correct, not tried it.";
let vowelRegex = /a|e|i|o|u/ig; // Change this line
let result = quoteSample.match(vowelRegex); // Change this line
2

This wouldn’t pass the challenge, where is the string you need to use the method on?

I don’t know about class and OR, tho

4

Oops, I had put let result = vowelRegex.match(vowelRegex); instead of let result = quoteSample.match(vowelRegex);. After fixing I was able to confirm the character class and OR have the same result.

5

They do essentially the same thing for single characters. However, you can also use the OR operator for groups of characters:

const friends = /Frankie|Mel|Kris/;

friends.test('Mel'); // true
friends.test('Andie'); // false

You can’t do this with character classes, but character classes are handy because they’re a more concise syntax if you’re dealing with single characters. You can think of it as syntactic sugar.

Some characters are also interpreted differently within character classes:

const first = /./; // matches any character
const second = /[.]/; // matches a literal period
const third = /\./; // same as second, due to being backslash escaped
2 Likes
6

Thanks for your insight!