I want a regex to match a simple hashtag like that in twitter (e.g. #someword). I want it also to recognize non standard characters (like those in Spanish, Hebrew or Chinese).
This was my initial regex: (^|\s|\b)(#(\w+))\b
--> but it doesn't recognize non standard characters.
Then, I tried using XRegExp.js, which worked, but ran too slowly.
Any suggestions for how to do it?
Eventually I found this: twitter-text.js useful link, which is basically how twitter solve this problem.
With native JS regexes that don't support unicode, your only option is to explicitly enumerate characters that can end the tag and match everything else, for example:
> s = "foo #הַתִּקְוָה. bar"
"foo #הַתִּקְוָה. bar"
> s.match(/#(.+?)(?=[\s.,:,]|$)/)
["#הַתִּקְוָה", "הַתִּקְוָה"]
The [\s.,:,] should include spaces, punctuation and whatever else can be considered a terminating symbol.
#([^#]+)[\s,;]*
Explanation: This regular expression will search for a # followed by one or more non-# characters, followed by 0 or more spaces, commas or semicolons.
var input = "#hasta #mañana #babהַ";
var matches = input.match(/#([^#]+)[\s,;]*/g);
Result:
["#hasta ", "#mañana ", "#babהַ"]
EDIT - Replaced \b for word boundary
Related
I am implementing a javascript code which makes hashtag linkable as follows -
str2 = str.replace(/(^|\s)#([A-Za-z0-9é_ü]+)/gi, '$1#$2');
if you see i included special hungarian characters like é , ü ... to be included in the hashtag linking but above code break at those special hungarian chars. But when i test that in w3schools.com example code editor things work there. So in my local script file those special chars are not being recognized as a character(é) but look like it's being treated as "e" character. Why this is happening ? how to overcome this problems, please suggest ideas.
Look here and here. Javascript has some problems with Unicode in regexp.
If you want to match every Unicode letter, you should use this regexp [\u00C0-\u1FFF\u2C00-\uD7FF\w].
So your code should look like this:
str2 = str.replace(/(^|\s)#([\u00C0-\u1FFF\u2C00-\uD7FF\w]+)/gi, '$1#$2');
var str2 = 'abc #łążaf3234 efg'.replace(/(^|\s)#([\u00C0-\u1FFF\u2C00-\uD7FF\w]+)/gi, '$1#$2');
alert(str2);
You have to list the special characters [A-Za-z0-9éüíóþæöÉÚÍÓÞÆÖ] (these are icelandic characters) or you could use \S to match any non-whitespace character
Your best bet is to use unicode escape sequences (like \u2665) rather than the binary character.
I am building a JSON validator from scratch, but I am quite stuck with the string part. My hope was building a regex which would match the following sequence found on JSON.org:
My regex so far is:
/^\"((?=\\)\\(\"|\/|\\|b|f|n|r|t|u[0-9a-f]{4}))*\"$/
It does match the criteria with a backslash following by a character and an empty string. But I'm not sure how to use the UNICODE part.
Is there a regex to match any UNICODE character expert " or \ or control character? And will it match a newline or horizontal tab?
The last question is because the regex match the string "\t", but not " " (four spaces, but the idea is to be a tab). Otherwise I will need to expand the regex with it, which is not a problem, but my guess is the horizontal tab is a UNICODE character.
Thanks to Jaeger Kor, I now have the following regex:
/^\"((?=\\)\\(\"|\/|\\|b|f|n|r|t|u[0-9a-f]{4})|[^\\"]*)*\"$/
It appears to be correct, but is there any way to check for control characters or is this unneeded as they appear on the non-printable characters on regular-expressions.info? The input to validate is always text from a textarea.
Update: the regex is as following in case anyone needs it:
/^("(((?=\\)\\(["\\\/bfnrt]|u[0-9a-fA-F]{4}))|[^"\\\0-\x1F\x7F]+)*")$/
For your exact question create a character class
# Matches any character that isn't a \ or "
/[^\\"]/
And then you can just add * on the end to get 0 or unlimited number of them or alternatively 1 or an unlimited number with +
/[^\\"]*/
or
/[^\\"]+/
Also there is this below, found at https://regex101.com/ under the library tab when searching for json
/(?(DEFINE)
# Note that everything is atomic, JSON does not need backtracking if it's valid
# and this prevents catastrophic backtracking
(?<json>(?>\s*(?&object)\s*|\s*(?&array)\s*))
(?<object>(?>\{\s*(?>(?&pair)(?>\s*,\s*(?&pair))*)?\s*\}))
(?<pair>(?>(?&STRING)\s*:\s*(?&value)))
(?<array>(?>\[\s*(?>(?&value)(?>\s*,\s*(?&value))*)?\s*\]))
(?<value>(?>true|false|null|(?&STRING)|(?&NUMBER)|(?&object)|(?&array)))
(?<STRING>(?>"(?>\\(?>["\\\/bfnrt]|u[a-fA-F0-9]{4})|[^"\\\0-\x1F\x7F]+)*"))
(?<NUMBER>(?>-?(?>0|[1-9][0-9]*)(?>\.[0-9]+)?(?>[eE][+-]?[0-9]+)?))
)
\A(?&json)\z/x
This should match any valid json, you can also test it at the website above
EDIT:
Link to the regex
Use this, works also with array jsons [{...},{...}]:
((\[[^\}]{3,})?\{s*[^\}\{]{3,}?:.*\}([^\{]+\])?)
Demo:
https://regex101.com/r/aHAnJL/1
I have a problem using a Javascript-Regexp.
This is a very simplified regexp, which demonstrates my Problem:
(?:\s(\+\d\w*))|(\w+)
This regex should only match strings, that doesn't contain forbidden characters (everything that is no word-character).
The only exception is the Symbol +
A match is allowed to start with this symbol, if [0-9] is trailing.
And a + must not appear within words (44+44 is not a valid match, but +4ad is)
In order to allow the + only at the beginning, I said that there must be a whitespace preceding. However, I don't want the whitespace to be part of the match.
I tested my regex with this tool: http://regex101.com/#javascript and the resultig matches look fine.
There are 2 Issues with that regexp:
If I use it in my JS-Code, the space is always part of the match
If +42 appears at the beginning of a line, it won't be matched
My Questions:
How should the regex look like?
Why does this regex add the space to the matches?
Here's my JS-Code:
var input = "+5ad6 +5ad6 sd asd+as +we";
var regexp = /(?:\s(\+\d\w*))|(\w+)/g;
var tokens = input.match(regexp);
console.log(tokens);
How should the regex look like?
You've got multiple choices to reach your goal:
It's fine as you have it. You might allow the string beginning in place of the whitespace as well, though. Just get the capturing groups (tokens[1], tokens[2]) out of it, which will not include the whitespace.
If you didn't use JavaScript, a lookbehind could help. Unfortunately it's not supported.
Require a non-word-boundary before the +, which would make every \w character before the + prevent the match:
/\B\+\d\w+|\w+/
Why does this regex add the space to the matches?
Because the regex does match the whitespace. It does not add the \s(\+\d\w+) to the captured groups, though.
I want a regex to match a simple hashtag like that in twitter (e.g. #someword). I want it also to recognize non standard characters (like those in Spanish, Hebrew or Chinese).
This was my initial regex: (^|\s|\b)(#(\w+))\b
--> but it doesn't recognize non standard characters.
Then, I tried using XRegExp.js, which worked, but ran too slowly.
Any suggestions for how to do it?
Eventually I found this: twitter-text.js useful link, which is basically how twitter solve this problem.
With native JS regexes that don't support unicode, your only option is to explicitly enumerate characters that can end the tag and match everything else, for example:
> s = "foo #הַתִּקְוָה. bar"
"foo #הַתִּקְוָה. bar"
> s.match(/#(.+?)(?=[\s.,:,]|$)/)
["#הַתִּקְוָה", "הַתִּקְוָה"]
The [\s.,:,] should include spaces, punctuation and whatever else can be considered a terminating symbol.
#([^#]+)[\s,;]*
Explanation: This regular expression will search for a # followed by one or more non-# characters, followed by 0 or more spaces, commas or semicolons.
var input = "#hasta #mañana #babהַ";
var matches = input.match(/#([^#]+)[\s,;]*/g);
Result:
["#hasta ", "#mañana ", "#babהַ"]
EDIT - Replaced \b for word boundary
In JavaScript:
"ab abc cab ab ab".replace(/\bab\b/g, "AB");
correctly gives me:
"AB abc cab AB AB"
When I use utf-8 characters though:
"αβ αβγ γαβ αβ αβ".replace(/\bαβ\b/g, "AB");
the word boundary operator doesn't seem to work:
"αβ αβγ γαβ αβ αβ"
Is there a solution to this?
The word boundary assertion does only match if a word character is not preceded or followed by another word character (so .\b. is equal to \W\w and \w\W). And \w is defined as [A-Za-z0-9_]. So \w doesn’t match greek characters. And thus you cannot use \b for this case.
What you could do instead is to use this:
"αβ αβγ γαβ αβ αβ".replace(/(^|\s)αβ(?=\s|$)/g, "$1AB")
Not all Javascript regexp implementation has support for Unicode ad so you need to escape it
"αβ αβγ γαβ αβ αβ".replace(/\u03b1\u03b2/g, "AB"); // "AB ABγ γAB AB AB"
For mapping the characters you can take a look at http://htmlhelp.com/reference/html40/entities/symbols.html
Of course, this doesn't help with the word boundary issue (as explained in other answers) but should at least enable you to match the characters properly
I needed something to be programmable and handle punctuation, brackets, etc.
http://jsfiddle.net/AQvyd/
var wordToReplace = '買い手',
replacementWord = '[[BUYER]]',
text = 'Mange 買い手 information. The selected Store and Classification will be the default on the สั่งซื้อ.'
function replaceWord(text, wordToReplace, replacementWord) {
var re = new RegExp('(^|\\s|\\(|\'|"|,|;)' + wordToReplace + '($|\\s|\\)|\\.|\'|"|!|,|;|\\?)', 'gi');
return text.replace(re, replacementWord);
}
I've written a javascript resource editor so this is why I've found this page and also answered it out of necessity since I couldn't find a word boundary parametarized regexp that worked well for Unicode.
Not all the implementations of RegEx associated with Javascript engines a unicode aware.
For example Microsofts JScript using in IE is limited to ANSI.
When you’re dealing with Unicode and natural-language words, you probably want to be more careful with boundaries than just using \b. See this answer for details and directions.