I am building search and I am going to use javascript autocomplete with it. I am from Finland (finnish language) so I have to deal with some special characters like ä, ö and å
When user types text in to the search input field I try to match the text to data.
Here is simple example that is not working correctly if user types for example "ää". Same thing with "äl"
var title = "this is simple string with finnish word tämä on ääkköstesti älkää ihmetelkö";
// Does not work
var searchterm = "äl";
// does not work
//var searchterm = "ää";
// Works
//var searchterm = "wi";
if ( new RegExp("\\b"+searchterm, "gi").test(title) ) {
$("#result").html("Match: ("+searchterm+"): "+title);
} else {
$("#result").html("nothing found with term: "+searchterm);
}
http://jsfiddle.net/7TsxB/
So how can I get those ä,ö and å characters to work with javascript regex?
I think I should use unicode codes but how should I do that? Codes for those characters are:
[\u00C4,\u00E4,\u00C5,\u00E5,\u00D6,\u00F6]
=> äÄåÅöÖ
There appears to be a problem with Regex and the word boundary \b matching the beginning of a string with a starting character out of the normal 256 byte range.
Instead of using \b, try using (?:^|\\s)
var title = "this is simple string with finnish word tämä on ääkköstesti älkää ihmetelkö";
// Does not work
var searchterm = "äl";
// does not work
//var searchterm = "ää";
// Works
//var searchterm = "wi";
if ( new RegExp("(?:^|\\s)"+searchterm, "gi").test(title) ) {
$("#result").html("Match: ("+searchterm+"): "+title);
} else {
$("#result").html("nothing found with term: "+searchterm);
}
Breakdown:
(?: parenthesis () form a capture group in Regex. Parenthesis started with a question mark and colon ?: form a non-capturing group. They just group the terms together
^ the caret symbol matches the beginning of a string
| the bar is the "or" operator.
\s matches whitespace (appears as \\s in the string because we have to escape the backslash)
) closes the group
So instead of using \b, which matches word boundaries and doesn't work for unicode characters, we use a non-capturing group which matches the beginning of a string OR whitespace.
The \b character class in JavaScript RegEx is really only useful with simple ASCII encoding. \b is a shortcut code for the boundary between \w and \W sets or \w and the beginning or end of the string. These character sets only take into account ASCII "word" characters, where \w is equal to [a-zA-Z0-9_] and \W is the negation of that class.
This makes the RegEx character classes largely useless for dealing with any real language.
\s should work for what you want to do, provided that search terms are only delimited by whitespace.
this question is old, but I think I found a better solution for boundary in regular expressions with unicode letters.
Using XRegExp library you can implement a valid \b boundary expanding this
XRegExp('(?=^|$|[^\\p{L}])')
the result is a 4000+ char long, but it seems to work quite performing.
Some explanation: (?= ) is a zero-length lookahead that looks for a begin or end boundary or a non-letter unicode character. The most important think is the lookahead, because the \b doesn't capture anything: it is simply true or false.
\b is a shortcut for the transition between a letter and a non-letter character, or vice-versa.
Updating and improving on max_masseti's answer:
With the introduction of the /u modifier for RegExs in ES2018, you can now use \p{L} to represent any unicode letter, and \P{L} (notice the uppercase P) to represent anything but.
EDIT: Previous version was incomplete.
As such:
const text = 'A Fé, o Império, e as terras viciosas';
text.split(/(?<=\p{L})(?=\P{L})|(?<=\P{L})(?=\p{L})/);
// ['A', ' Fé', ',', ' o', ' Império', ',', ' e', ' as', ' terras', ' viciosas']
We're using a lookbehind (?<=...) to find a letter and a lookahead (?=...) to find a non-letter, or vice versa.
I would recommend you to use XRegExp when you have to work with a specific set of characters from Unicode, the author of this library mapped all kind of regional sets of characters making the work with different languages easier.
Despite the fact the issue seems to be 8 years old, I run into a similar problem (I had to match Cyrillic letters) not so far ago. I spend a whole day on this and could not find any appropriate answer here on StackOverflow. So, to avoid others making lots of effort, I'd like to share my solution.
Yes, \b word boundary works only with Latin letters (Word boundary: \b):
Word boundary \b doesn’t work for non-Latin alphabets
The word boundary test \b checks that there should be \w on the one side from the position and "not \w" – on the other side.
But \w means a Latin letter a-z (or a digit or an underscore), so the test doesn’t work for other characters, e.g. Cyrillic letters or hieroglyphs.
Yes, JavaScript RegExp implementation hardly supports UTF-8 encoding.
So, I tried implementing own word boundary feature with the support of non-Latin characters. To make word boundary work just with Cyrillic characters I created such regular expression:
new RegExp(`(?<![\u0400-\u04ff])${cyrillicSearchValue}(?![\u0400-\u04ff])`,'gi')
Where \u0400-\u04ff is a range of Cyrillic characters provided in the table of codes. It is not an ideal solution, however, it works properly in most cases.
To make it work in your case, you just have to pick up an appropriate range of codes from the list of Unicode characters.
To try out my example run the code snippet below.
function getMatchExpression(cyrillicSearchValue) {
return new RegExp(
`(?<![\u0400-\u04ff])${cyrillicSearchValue}(?![\u0400-\u04ff])`,
'gi',
);
}
const sentence = 'Будь-який текст кирилицею, де необхідно знайти слово з контексту';
console.log(sentence.match(getMatchExpression('текст')));
// expected output: ["текст"]
console.log(sentence.match(getMatchExpression('но')));
// expected output: null
I noticed something really weird with \b when using Unicode:
/\bo/.test("pop"); // false (obviously)
/\bä/.test("päp"); // true (what..?)
/\Bo/.test("pop"); // true
/\Bä/.test("päp"); // false (what..?)
It appears that meaning of \b and \B are reversed, but only when used with non-ASCII Unicode? There might be something deeper going on here, but I'm not sure what it is.
In any case, it seems that the word boundary is the issue, not the Unicode characters themselves. Perhaps you should just replace \b with (^|[\s\\/-_&]), as that seems to work correctly. (Make your list of symbols more comprehensive than mine, though.)
My idea is to search with codes representing the Finnish letters
new RegExp("\\b"+asciiOnly(searchterm), "gi").test(asciiOnly(title))
My original idea was to use plain encodeURI but the % sign seemed to interfere with the regexp.
http://jsfiddle.net/7TsxB/5/
I wrote a crude function using encodeURI to encode every character with code over 128 but removing its % and adding 'QQ' in the beginning. It is not the best marker but I couldn't get non alphanumeric to work.
What you are looking for is the Unicode word boundaries standard:
http://unicode.org/reports/tr29/tr29-9.html#Word_Boundaries
There is a JavaScript implementation here (unciodejs.wordbreak.js)
https://github.com/wikimedia/unicodejs
I had a similar problem, where I was trying to replace all of a particular unicode word with a different unicode word, and I cannot use lookbehind because it's not supported in the JS engine this code will be used in. I ultimately resolved it like this:
const needle = "КАРТОПЛЯ";
const replace = "БАРАБОЛЯ";
const regex = new RegExp(
String.raw`(^|[^\n\p{L}])`
+ needle
+ String.raw`(?=$|\P{L})`,
"gimu",
);
const result = (
'КАРТОПЛЯ сдффКАРТОПЛЯдадф КАРТОПЛЯ КАРТОПЛЯ КАРТОПЛЯ??? !!!КАРТОПЛЯ ;!;!КАРТОПЛЯ/#?#?'
+ '\n\nКАРТОПЛЯ КАРТОПЛЯ - - -КАРТОПЛЯ--'
)
.replace(regex, function (match, ...args) {
return args[0] + replace;
});
console.log(result)
output:
БАРАБОЛЯ сдффКАРТОПЛЯдадф БАРАБОЛЯ БАРАБОЛЯ БАРАБОЛЯ??? !!!БАРАБОЛЯ ;!;!БАРАБОЛЯ/#?#?
БАРАБОЛЯ БАРАБОЛЯ - - -БАРАБОЛЯ--
Breaking it apart
The first regex: (^|[^\n\p{L}])
^| = Start of the line or
[^\n\p{L}] = Any character which is not a letter or a newline
The second regex: (?=$|\P{L})
?= = Lookahead
$| = End of the line or
\P{L} = Any character which is not a letter
The first regex captures the group and is then used via args[0] to put it back into the string during replacement, thereby avoiding a lookbehind. The second regex utilized lookahead.
Note that the second one MUST be a lookahead because if we capture it then overlapping regex matches will not trigger (e.g. КАРТОПЛЯ КАРТОПЛЯ КАРТОПЛЯ would only match on the 1st and 3rd ones).
Trying to find text "myTest":
/(?<![\p{L}\p{N}_])myTest(?![\p{L}\p{N}_])/gu
Similar to NetBeans or Notepad++ form. Trying to find the expression without any letter or number or underscore (like \w characters of word boundary \b) in any unicode characters of letter and number before or after the expression.
I have had a similar problem, but I had to replace an array of terms. All solutions, which I have found did not worked, if two terms were in the text next to each other (because their boundaries overlaped). So I had to use a little modified approach:
var text = "Ještě. že; \"už\" à. Fürs, 'anlässlich' že že že.";
var terms = ["à","anlässlich","Fürs","už","Ještě", "že"];
var replaced = [];
var order = 0;
for (i = 0; i < terms.length; i++) {
terms[i] = "(^\|[ \n\r\t.,;'\"\+!?-])(" + terms[i] + ")([ \n\r\t.,;'\"\+!?-]+\|$)";
}
var re = new RegExp(terms.join("|"), "");
while (true) {
var replacedString = "";
text = text.replace(re, function replacer(match){
var beginning = match.match("^[ \n\r\t.,;'\"\+!?-]+");
if (beginning == null) beginning = "";
var ending = match.match("[ \n\r\t.,;'\"\+!?-]+$");
if (ending == null) ending = "";
replacedString = match.replace(beginning,"");
replacedString = replacedString.replace(ending,"");
replaced.push(replacedString);
return beginning+"{{"+order+"}}"+ending;
});
if (replacedString == "") break;
order += 1;
}
See the code in a fiddle: http://jsfiddle.net/antoninslejska/bvbLpdos/1/
The regular expression is inspired by: http://breakthebit.org/post/3446894238/word-boundaries-in-javascripts-regular
I can't say, that I find the solution elegant...
The correct answer to the question is given by andrefs.
I will only rewrite it more clearly, after putting all required things together.
For ASCII text, you can use \b for matching a word boundary both at the start and the end of a pattern. When using Unicode text, you need to use 2 different patterns for doing the same:
Use (?<=^|\P{L}) for matching the start or a word boundary before the main pattern.
Use (?=\P{L}|$) for matching the end or a word boundary after the main pattern.
Additionally, use (?i) in the beginning of everything, to make all those matchings case-insensitive.
So the resulting answer is: (?i)(?<=^|\P{L})xxx(?=\P{L}|$), where xxx is your main pattern. This would be the equivalent of (?i)\bxxx\b for ASCII text.
For your code to work, you now need to do the following:
Assign to your variable "searchterm", the pattern or words you want to find.
Escape the variable's contents. For example, replace '\' with '\\' and also do the same for any reserved special character of regex, like '\^', '\$', '\/', etc. Check here for a question on how to do this.
Insert the variable's contents to the pattern above, in the place of "xxx", by simply using the string.replace() method.
bad but working:
var text = " аб аб АБ абвг ";
var ttt = "(аб)"
var p = "(^|$|[^A-Za-zА-Я-а-я0-9()])"; // add other word boundary symbols here
var exp = new RegExp(p+ttt+p,"gi");
text = text.replace(exp, "$1($2)$3").replace(exp, "$1($2)$3");
const t1 = performance.now();
console.log(text);
result (without qutes):
" (аб) (аб) (АБ) абвг "
I struggled hard on this. Working with French accented characters, and I managed to find this solution :
const myString = "MyString";
const regex = new RegExp(
"(?:[^À-ú]|^)\\b(" + myString + ")\\b(?:[^À-ú]|$)",
"ig"
);
What id does :
It keeps checking word-boundaries with \b before and after "MyString".
In addition to that, (?:[^À-ú]|^) and (?:[^À-ú]|$) will check if MyString is not surrounded by any accented characters
It will not work with cyrillic but it may be possible to find the range of cirillic charactes and edit [^À-ú] in consequence.
Warning, it captures only the group (MyString) but the total match contains previous and next characters
See example : https://regex101.com/r/5P0ZIe/1
Match examples :
MyString
match : "MyString"
group 1 : "MyString"
Lorem ipsum. MyString dolor sit amet
match : " MyString "
group 1 : "MyString"
(MyString)
match : "(MyString)"
group 1 : "MyString"
BetweenCharactersMyStringIsNotFound
match : Nothing
group 1 : Nothing
éMyStringé
match : Nothing
group 1 : Nothing
ùMyString
match : Nothing
group 1 : Nothing
MyStringÖ
match : Nothing
group 1 : Nothing
I am trying to split a string using a regular expression for links (urls).
The regex in question is
var regex = new RegExp('(?:^(?:(?:[a-z]+:)?//)(?:\S+(?::\S*)?#)?(?:localhost|(?:(?:[a-z\u00a1-\uffff0-9]-*)*[a-z\u00a1-\uffff0-9]+)(?:\.(?:[a-z\u00a1-\uffff0-9]-*)*[a-z\u00a1-\uffff0-9]+)*(?:\.(?:[a-z\u00a1-\uffff]{2,})))(?::\d{2,5})?(?:[/?#]\S*)?$)')
If i do
regex.test("https://google.com"); // returns true
but doing -
"Go to https://google.com".split(regex);
// return ["Go to https://google.com"]
Whereas i expect it to return
["Go to ", "https://google.com"]
Any idea what's going on here?
First of all, you're using a string literal to build your regex, which means that you have to escape your backslashes (since a backslash has a special meaning in strings, used for the line feed char \n for example):
var regex = new RegExp('(?:^(?:(?:[a-z]+:)?//)(?:\\S+(?::\\S*)?#)?(?:localhost|(?:(?:[a-z\\u00a1-\\uffff0-9]-*)*[a-z\\u00a1-\\uffff0-9]+)(?:\\.(?:[a-z\\u00a1-\\uffff0-9]-*)*[a-z\\u00a1-\\uffff0-9]+)*(?:\\.(?:[a-z\\u00a1-\\uffff]{2,})))(?::\\d{2,5})?(?:[/?#]\\S*)?$)');
Another solution would be to use the regex literal, as JavaScript proposes one, but you would then have to escape the slashes:
var regex = /(?:^(?:(?:[a-z]+:)?\/\/)(?:\S+(?::\S*)?#)?(?:localhost|(?:(?:[a-z\u00a1-\uffff0-9]-*)*[a-z\u00a1-\uffff0-9]+)(?:\.(?:[a-z\u00a1-\uffff0-9]-*)*[a-z\u00a1-\uffff0-9]+)*(?:\.(?:[a-z\u00a1-\uffff]{2,})))(?::\d{2,5})?(?:[\/?#]\S*)?$)/;
Then, your regex will try to match against the entire input due to the ^ and $ anchors. So if you remove them (or better, replace them with word boundaries \b), you'll be able to find URLs in a string for example:
var regex = /(?:\b(?:(?:[a-z]+:)?\/\/)(?:\S+(?::\S*)?#)?(?:localhost|(?:(?:[a-z\u00a1-\uffff0-9]-*)*[a-z\u00a1-\uffff0-9]+)(?:\.(?:[a-z\u00a1-\uffff0-9]-*)*[a-z\u00a1-\uffff0-9]+)*(?:\.(?:[a-z\u00a1-\uffff]{2,})))(?::\d{2,5})?(?:[\/?#]\S*)?\b)/;
But, the main point is that you're misunderstanding the split concept. Given the string "hello world", if you split by space, you'll end up with ["hello", "world"]: no more space anymore since it was the char that was used to split.
That is, if you split by the URL regex, the output array won't contain the URLs anymore. It seems to me that a lookahead could suit your needs:
var regex = /(?=(?:\b(?:(?:[a-z]+:)?\/\/)(?:\S+(?::\S*)?#)?(?:localhost|(?:(?:[a-z\u00a1-\uffff0-9]-*)*[a-z\u00a1-\uffff0-9]+)(?:\.(?:[a-z\u00a1-\uffff0-9]-*)*[a-z\u00a1-\uffff0-9]+)*(?:\.(?:[a-z\u00a1-\uffff]{2,})))(?::\d{2,5})?(?:[\/?#]\S*)?\b))/;
"Go to https://google.com".split(regex) // ["Go to ", "https://google.com"]
The regex explained:
(?=(?:\b(?:(?:[a-z]+:)?//)(?:\S+(?::\S*)?#)?(?:localhost|(?:(?:[a-z\u00a1-\uffff0-9]-*)*[a-z\u00a1-\uffff0-9]+)(?:\.(?:[a-z\u00a1-\uffff0-9]-*)*[a-z\u00a1-\uffff0-9]+)*(?:\.(?:[a-z\u00a1-\uffff]{2,})))(?::\d{2,5})?(?:[/?#]\S*)?\b))
Debuggex Demo
By splitting a string with a positive lookahead (?=content_of_lookahead), you'll split by each interchar that is followed by the content of the lookahead.
Take a look at 8 Regular Expressions You Should Know.
To match an url you can use following regex :
var regex = "(https?:\/\/)?([\da-z\.-]+)\.([a-z\.]{2,6})([\/\w# \.-]*)*\/?$";
"Go to https://google.com".split(regex);
// return ["https://google.com"]
Live example.
Hope this helps.
I want to write a regex pattern that matches for full words or phrases even if they have unicode chars to wrap them with some html code. So I use this pattern:
var pattern=new RegExp('(^|\\s)'+phrase+'(?=\\s|$)', "gi");
It works perfectly even on multi-word phrases expect for one issue. If the phrase isn't the start of the string, it matches with the space before the word. So after I wrap it I'll lose that space. I only want to wrap the phrase variable and not the spaces.
For example:
var string="This is a nice sentence.";
var phrase="is a nice";
/*OUTPUT: Thisis a nicesentence*//*HTML OUTPUT: This<span>is a nice</span>sentence*/
/*What I want: This <span>is a nice</span> sentence*/
Of course this pattern could work:
var pattern=new RegExp(phrase, "gi");
But I'm not looking for those strings that are substrings of another.
Is it possible to solve my issue with a better regex pattern?
Simply write back what you captured in group 1:
output = string.replace(pattern, '$1<span>' + phrase + '</span>');
If you are not using replace but match or exec and do the replacement manually, you can still access the capturing group in the returned array and insert the space or empty string before your span.
By the way, if you capture the phrase as well, you don't need any string concatenation in the replacement:
var pattern = new RegExp('(^|\\s)('+phrase+')(?=\\s|$)', "gi");
output = string.replace(pattern, '$1<span>$2</span>');
I use some jquery to highlight search results. For some reason if i enter a basis dot, all of the text get selected. I use regex and replace to wrap the results in a tag to give the found matches a color.
the code that i use
var pattern = new.RegExp('('+$.unique(text.split(" ")).join("|")+")","gi");
how can i prevent that the dot selects all text, so i want to leave the point out of the code(the dot has no power)
You may be able to get there by doing this:
var pattern = new.RegExp('('+$.unique(text.replace('.', '\\.').split(" ")).join("|")+")","gi");
The idea here is that you're attempting to escape the period, which acts as a wild card in regex.
This will replace all special RegExp characters (except for | since you're using that to join the terms) with their escaped version so you won't get unwanted matches or syntax errors:
var str = $.unique(text.split(" ")).join("|"),
pattern;
str = str.replace(/[\\\.\+\*\?\^\$\[\]\(\)\{\}\/\'\#\:\!\=]/ig, "\\$&");
pattern = new RegExp('('+str+')', 'gi');
The dot is supposed to match all text (almost everything, really). If you want to match a period, you can just escape it as \..
If you have a period in your RegExp it's supposed to match any character besides newline characters. If you don't want that functionality you need to escape the period.
Example RegExp with period escaped /word\./
You need to escape the text you're putting into the regex, so that special characters don't have unwanted meanings. My code is based on some from phpjs.org:
var words = $.unique(text.split(" ")).join("|");
words = words.replace(/[.\\+*?\[\^\]$(){}=!<>|:\\-]/h, '\\$&'); // escape regex special chars
var pattern = new RegExp('(' + words + ")","gi");
This escapes the following characters: .\+*?[^]$(){}=!<>|:- with a backslash \ so you can safely insert them into your new RegExp construction.