javascript comparison of strings - Stack Overflow

I have the following script

document.write("12" < "2");

which returns true. Any reason why? The documentation says that javascript pares strings numerically but, I don't see how "12" is less than "2".

I have the following script

document.write("12" < "2");

which returns true. Any reason why? The documentation says that javascript pares strings numerically but, I don't see how "12" is less than "2".

• javascript
• string

Share Improve this question Follow asked Jun 5, 2013 at 22:38 RobertRobert 10.4k2020 gold badges8989 silver badges140140 bronze badges 4

• 3 What documentation did you see that in? It is incorrect. They're pared lexicographically. – Paul Commented Jun 5, 2013 at 22:40
• developer.mozilla/en-US/docs/Web/JavaScript/Guide/… – Robert Commented Jun 5, 2013 at 22:43
• 1 The page you linked to says "Strings are pared based on standard lexicographical ordering, using Unicode values." That means that '12' < '2' just like 'a2' < 'b'. – Paul Commented Jun 5, 2013 at 22:46
• @Paulpro - Got it (sorry). Didn't realize that came from the OP. Deleting my ment.... – jahroy Commented Jun 5, 2013 at 22:53

Add a ment  | 

4 Answers 4

Sorted by: Reset to default 10

JavaScript pares strings character by character until one of the characters is different.

1 is less than 2 so it stops paring after the first character.

I believe it is doing a lexicographic parison - the first char in string one is '1', which is less than the first char of string two, which is '2'. More about Lexicographic order here: http://en.wikipedia/wiki/Lexicographical_order

This is because the first character of "12" is 1, which es before "2"; and JavaScript string parison is lexically/alphabetically, rather than numerically. Though it appears partially numeric, since 1 is sorted ahead of 2.

You can, however, simply pare the numbers as numbers:

document.write(parseFloat("12") < parseFloat("2"));

Try:

document.write(parseInt("12") < parseInt("2"));