Is there any way to find which input character fails the regex pattern.
For ex: consider [A-Za-z\s.&] is only allowable but the user enter like "test/string" where '/' invalidates input. How to find who fails regex (our case '/')
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all answers are good. RoToRa perfectly matches my need. thank uArK– ArK2010-04-29 10:50:47 +00:00Commented Apr 29, 2010 at 10:50
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3 Answers
You could remove the valid chars and you'll have a string of the invalid ones:
var invalid = "test/string".replace(/[A-Za-z\s.&]/g,""); // results in "/"
Comments
Just negate your character class and find out which character(s) match.
[^A-Za-z\s.&]
will match the / in test/string. So, altogether you get
if (/^[A-Za-z\s.&]+$/.test(subject)) {
// Successful match
} else {
result = subject.match(/[^A-Za-z\s.&]/g);
// result is an array that contains all the characters that failed the match
}
Comments
To find which characters fails, split it with /[A-Za-z\s.&]+/, you will get invalid characters list
"test/string".split(/[A-Za-z\s.&]+/).join('')
/
To check username is valid or not, you could just use ^ and $ anchors.
/^[A-Za-z\s.&]+$/
1 Comment
Tim Pietzcker
I think he's got that part covered, but he wants to find out why the match failed, i. e. on which character.