i need to validate a field for empty. But it should allow English and the Foreign languages characters(UTF-8) but not the special characters. I'm not good at Regex. So any help on this would be great...
If you want to support a wide range of languages, you'll have to work by excluding only the characters you don't want, since specifying all of the ranges you do want will be difficult.
You'll need to look at the list of Unicode blocks and or the character database to identify the blocks you want to exclude (like, for instance, U+0000 through U+001F. This Wikipedia article may also help.
Then use a regular expression with character classes to look for what you want to exclude.
For example, this will check for the U+0000 through U+001F and the U+007F characters (obviously you'll be excluding more than just these):
if (/[\u0000-\u001F\u007F]/.exec(theString)) {
// Contains at least one invalid character
}
The [] identify a "character class" (list and/or range of characters to look for). That particular one says look for \u0000 through \u001F (inclusive) as well as \u007F.
It would have been nice if I could say "Just do /^\w+$/.test(word)", but...
See this answer for the current state of unicode support (or rather lack of) in JavaScript regular expressions.
You can either use the library he suggests, which might be slow or enlist the help of the server for this (which might be slower).
You can test for a unicode letter like this:
str.match(/\p{L}/u)
Or for the existence of a non-letter like this:
str.match(/[^\p{L}]/u)
Related
I have a dilemma here. I am trying to write a regex pattern that matches all alpha characters for eastern languages as well as western languages. One of the criteria is that no numbers can match (so José13) is not a match but (José) is, the other criteria is that special characters cannot match (ie: !##$% etc.)
I've played around with this in chrome's console, and I've gotten:
"a".match('[a-zA-z]');
to come back successfully, when I put in:
"a".match('[\p{L}]');
I get a null response, which I'm not quite understanding why. According to http://www.regular-expressions.info/unicode.html \p{L} is a match for any letter.
EDIT: the \p doesn't seem to work in my chrome console, so I'll try a different route. I have a chart of the unicode from Unifoundry. I'll match up the regex and attempt to make the range of characters invalid.
Any input would be greatly appreciated.
This works in the javascript console, but it seems like a hack:
.match('^[^\u0000-\u0040\u005B-\u0060\u007B-\u00BF\u00D7\u00F7]*');
However it does what I need it to do.
Referenced this post on SO: Javascript + Unicode regexes
Current Javascript implementations don't support such shortcuts, but you can specify a range, for example:
/[\u4E00-\u9FFF]+/g.test("漢字")
I am looking to find this in a string: XXXX-XXX-XXX Where the X is any number.
I need to find this in a string using JavaScript so bonus points to those who can provide me the JavaScript too. I tried to create a regex and came out with this: ^[0-9]{4}\-[0-9]{3}\-[0-9]{3}$
Also, I would love to know of any cheat sheets or programs you guys use to create your regular expressions.
i suppose this is what you want:
\d{4}-\d{3}-\d{3}
in doubt? Google for "RegEx Testers"
With your attempt:
^[0-9]{4}\-[0-9]{3}\-[0-9]{3}$
Since the - is not a metacharacter, there is no need to escape it -- thus you are looking for explicit backslash characters.
Also, you've anchored the match at the beginning and end of the string -- this will match only strings that consist only of your number. (Well, assuming the rest were correct.)
I know most people like the {3} style of counting, but when the thing being matched is a single digit, I find this more legible:
\d\d\d\d-\d\d\d-\d\d\d
Obviously if you wanted to extend this to matching hexadecimal digits, extending this one would be horrible, but I think this is far more legible than alternatives:
\d{4}-\d{3}-\d{3}
[[:digit:]]{4}-[[:digit:]]{3}-[[:digit:]]{3}
[0-9]{4}-[0-9]{3}-[0-9]{3}
Go with whatever is easiest for you to read.
I tend to use the perlre(1) manpage as my main reference, knowing full well that it is far more featureful than many regexp engines. I'm prepared to handle the differences considering how conveniently available the perlre manpage is on most systems.
var result = (/\d{4}\-\d{3}\-\d{3}/).exec(myString);
In the text page, I would like to examine each word. What is the best way to read each word at the time? It is easy to find words that are surrounded by space, but once you get into parsing out words in text it can get complicated.
Instead of defining my own way of parsing the words from text, is there something already built that parse out the words in regular expression or other methods?
Some example of words in text.
word word. word(word) word's word word' "word" .word. 'word' sub-word
You can use:
text = "word word. word(word) word's word word' \"word\" .word. 'word' sub-word";
words = text.match(/[-\w]+/g);
This will give you an array with all your words.
In regular expressions, \w means any character that is either a-z, A-Z, 0-9 or _. [-\w] means any character that is a \w or a -. [-\w]+ means any of these characters that appear 1 ore more times.
If you would like to define a word as being something more than the above expression, add the other characters that compose your words inside the [-\w] character class. For example, if you'd like words to also contain ( and ), make the character class be [-\w()].
For an introduction in regular expressions, check out the great tutorial at regular-expressions.info.
What you're talking about is Tokenisation. It's non-trivial to say the least, and a subject of intense reasearch at the major search engines. There are a number of open source tokenisation libraries in various server-side languages (e.g see the Stanford NLP and Lucene projects) but as far as I am aware there's nothing that would even come close to these in javascript. You may have to roll your own :) or perhaps do the processing server-side, and load the results via AJAX?
I support Richard's answer here - but to add to it - one of the easiest ways of building a tokeniser (imho) is Antlr; and some maniac has built a Javascript target for it; thus allowing you to run and execute a grammar in the web browser (look under 'runtime libraries' section here)
I won't pretend that there's not a learning curve there though.
Take a look at regular expressions - you can define almost any parsing algorithm you want.
I have a regex that right now only allows lowercase letters, I need one that requires either lowercase or uppercase letters:
/(?=.*[a-z])/
You Can’t Get There from Here
I have a regex that right now only allows lowercase letters, I need one that requires either lowercase or uppercase letters: /(?=.*[a-z])/
Unfortunately, it is utterly impossible to do this correctly using Javascript! Read this flavor comparison’s ECMA column for all of what Javascript cannot do.
Theory vs Practice
The proper pattern for lowercase is the standard Unicode derived binary property \p{Lowercase}, and the proper pattern for uppercase is similarly \p{Uppercase}. These are normative properties that sometimes include non-letters in them under certain exotic circumstances.
Using just General Category properties, you can have \p{Ll} for Lowercase_Letter, \p{Lu} for Uppercase_Letter, and \p{Lt} for titlecase letter. Remember they are three cases in Unicode, not two). There is a standard alias \p{LC} which means [\p{Lu}\p{Lt}\p{Ll}].
If you want a letter than is not a lowercase letter, you could use (?=\P{Ll})\pL. Written in longhand that’s (?=\P{Lowercase_Letter})\p{Letter}. Again, these mix some of the Other_Lowercase code points that \p{Lowercase} recognizes. I must again stress that the Lowercase property is a superset of the Lowercase_Letter property.
Remember the previous paragraph, swapping in upper everywhere I have written lower, and you get the same thing for the capitals.
Possible Platforms
Because access to these essential properties is the minimal level of critical functionality necessary for Unicode regular expressions, some versions of Javascript implement them in just the way I have written them above. However, the standard for Javascript still does not require them, so you cannot in general count on them. This means that it is impossible to this correctly under all implementations of Javascript.
Languages in which it is possible to do what you want done minimally include:
C♯ and Java (both only General Categories)
Ruby if and only if v1.9 or better (only binary properties, including General Categories)
PHP and PCRE (only General Category and Script properties plus a couple extras)
ICU’s C++ library and Perl, which both support all Unicode properties
Of those listed bove, only the last line’s — ICU and Perl — strictly and completely meet all Level 1 compliance requirements (plus some Levels 2 and 3) for the proper handling of Unicode in regexes. However, all of those I’ve listed in the previous paragraph’s bullets can easily handle most, and quite probably all, of what you need.
Javascript is not amongst those, however. Your version might, though, if you are very lucky and never have to run on a standard-only Javascript platform.
Summary
So very sadly, you cannot really use Javascript regexes for Unicode work unless you have a non-standard extension. Some people do, but most do not. If you do not, you may have to use a different platform until the relevant ECMA standard catches up with the 21st century (Unicode 3.1 came out a decade ago!!).
If anyone knows of a Javascript library that implements the Level 1 requirements of UTS#18 on Unicode Regular Expressions including both RL1.2 “Properties” and RL1.2a “Annex C: Compatibility Properties”, please chime in.
Not sure if you mean mixed-case, or strictly lowercase plus strictly uppercase.
Here's the mixed-case version:
/^[a-zA-Z]+$/
And the strictly one-or-the-other version:
/^([a-z]+|[A-Z]+)$/
Try /(?=.*[a-z])/i
Note the i at the end, this makes the expression case insensitive.
Or add an uppercase range to your regex:
/(?=.*[a-zA-Z])/
Is there any way to disable all symbols, punctuations, block elements, geometric shapes and dingbats such like these:
✁ ✂ ✃ ✄ ✆ ✇ ✈ ✉ ✌ ✍ ✎ ✏ ✐ ✑ ✒ ✓ ✔ ✕ ⟻ ⟼ ⟽ ⟾ ⟿ ⟻ ⟼ ⟽ ⟾ ⟿ ▚ ▛ ▜ ▝ ▞ ▟
without writing down all of them in the Regular Expression Pattern, while enable all other normal language characters such like chinese, arabic etc.. such like these:
文化中国 الجزيرة نت
?
I'm building a javascript validation function and my real problem is that I can't use:
[a-zA-Z0-9]
Because this ignores a lots of languages too not just the symbols.
The Unicode standard divides up all the possible characters into code charts. Each code chart contains related characters. If you want to exclude (or include) only certain classes of characters, you will have to make a suitable list of exclusions (or inclusions). Unicode is big, so this might be a lot of work.
Not really.
JavaScript doesn't support Unicode Character Properties. The closest you'll get is excluding ranges by Unicode code point as Greg Hewgill suggested.
For example, to match all of the characters under Mathematical Symbols:
/[\u2190-\u259F]/
This depends on your regex dialect. Unfortunately, probably most existing JavaScript engines don't support Unicode character classes.
In regex engines such as the one in (recent) Perl or .Net, Unicode character classes can be referenced.
\p{L}: any kind of letter from any language.
\p{N}: any number symbol from any language (including, as I recall, the Indian and Arabic and CJK number glyphs).
Because Unicode supports composed and decomposed glyphs, you may run into certain complexities: namely, if only decomposed forms exist, it's possible that you might accidentally exclude some diacritic marks in your matching pattern, and you may need to explicitly allow glyphs of the type Mark. You can mitigate this somewhat by using, if I recall correctly, a string that has been normalized using kC normalization (only for characters that have a composed form). In environments that support Unicode well, there's usually a function that allows you to normalize Unicode strings fairly easily (true in Java and .Net, at least).
Edited to add: If you've started down this path, or have considered it, in order to regain some sanity, you may want to experiment with the Unicode Plugin for XRegExp (which will require you to take a dependency on XRegExp).
JavaScript regular expressions do not have native Unicode support. An alternative to to validate (or sanitize) the string at server site, or to use a non-native regex library. While I've never used it, XRegExp is such a library, and it has a Unicode Plugin.
Take a look at the Unicode Planes. You probably want to exclude everything but planes 0 and 2. After that, it gets ugly as you'll have to exclude a lot of plane 0 on a case-by-case basis.