undefined cast to a string with regex test
# Rick Waldron (13 years ago)
On Wednesday, October 10, 2012 at 6:19 AM, gaz Heyes wrote:
This wasn't totally unexpected but seriously made me go WTF. It appears that arguments to regexp.test are cast to a string. This was bad for me since I was writing a js parser at the time and checking the argument to see if it matched one of the reserved words. See the example below:-
if(/^(?:undefined|ok|wtf|js)$/.test(undefined)){ alert('WTF'); } else { alert('NO WTF'); }
This is by design and surely not a wtf. test() is specified to accept and operate on a string argument and therefore coerces it's arg to a string.
This is very common throughout ES
This wasn't totally unexpected but seriously made me go WTF. It appears that arguments to regexp.test are cast to a string. This was bad for me since I was writing a js parser at the time and checking the argument to see if it matched one of the reserved words. See the example below:-
if(/^(?:undefined|ok|wtf|js)$/.test(undefined)){ alert('WTF'); } else { alert('NO WTF'); }
That's pretty much all I got but if you didn't go WTF then I apologise for the wasted thread.
This wasn't totally unexpected but seriously made me go WTF. It appears that arguments to regexp.test are cast to a string. This was bad for me since I was writing a js parser at the time and checking the argument to see if it matched one of the reserved words. See the example below:- if(/^(?:undefined|ok|wtf|js)$/.test(undefined)){ alert('WTF'); } else { alert('NO WTF'); } That's pretty much all I got but if you didn't go WTF then I apologise for the wasted thread. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.mozilla.org/pipermail/es-discuss/attachments/20121010/f6eb4ed0/attachment.html>