in js (nodejs) i try to catch a specific word and this same word write with repeat letter ...
exemple, if i say world, i want catch this:
world woorld wwooorld worllddd worldddd
so i can juste make a for on my world an create a dynamique regexw with something like this:
var w = 'world';
var regex = '';
for(var i = 0; i < w.lengh; i++){
regex += `${w[i]}+`;
}
but can i do this only with one unique regex ?? ( or other original idea )
Your idea of constructing the regex is correct. You need however to take care that characters with a special meaning in regular expressions do not make things go wrong. So you could escape non-alphanumerical characters with a backslash:
var w = "world+hello";
var regex = new RegExp('^' + w.replace(/\W/g, '\\$&+').replace(/\w/g, '$&+') + '$');
console.log(regex, regex.test('wwoooorllldd++++hhelllo'));
The following pattern would match any combination of letter repeats for "world":
"w+o+r+l+d+"
The + denotes capturing 1 or more of the previous character.
Related
I would like to find all the matches of given strings (divided by spaces) in a string.
(The way for example, iTunes search box works).
That, for example, both "ab de" and "de ab" will return true on "abcde" (also "bc e a" or any order should return true)
If I replace the white space with a wild card, "ab*de" would return true on "abcde", but not "de*ab".
[I use * and not Regex syntax just for this explanation]
I could not find any pure Regex solution for that.
The only solution I could think of is spliting the search term and run multiple Regex.
Is it possible to find a pure Regex expression that will cover all these options ?
Returns true when all parts (divided by , or ' ') of a searchString occur in text. Otherwise false is returned.
filter(text, searchString) {
const regexStr = '(?=.*' + searchString.split(/\,|\s/).join(')(?=.*') + ')';
const searchRegEx = new RegExp(regexStr, 'gi');
return text.match(searchRegEx) !== null;
}
I'm pretty sure you could come up with a regex to do what you want, but it may not be the most efficient approach.
For example, the regex pattern (?=.*bc)(?=.*e)(?=.*a) will match any string that contains bc, e, and a.
var isMatch = 'abcde'.match(/(?=.*bc)(?=.*e)(?=.*a)/) != null; // equals true
var isMatch = 'bcde'.match(/(?=.*bc)(?=.*e)(?=.*a)/) != null; // equals false
You could write a function to dynamically create an expression based on your search terms, but whether it's the best way to accomplish what you are doing is another question.
Alternations are order insensitive:
"abcde".match(/(ab|de)/g); // => ['ab', 'de']
"abcde".match(/(de|ab)/g); // => ['ab', 'de']
So if you have a list of words to match you can build a regex with an alternation on the fly like so:
function regexForWordList(words) {
return new RegExp('(' + words.join('|') + ')', 'g');
}
'abcde'.match(['a', 'e']); // => ['a', 'e']
Try this:
var str = "your string";
str = str.split( " " );
for( var i = 0 ; i < str.length ; i++ ){
// your regexp match
}
This is script which I use - it works also with single word searchStrings
var what="test string with search cool word";
var searchString="search word";
var search = new RegExp(searchString, "gi"); // one-word searching
// multiple search words
if(searchString.indexOf(' ') != -1) {
search="";
var words=searchString.split(" ");
for(var i = 0; i < words.length; i++) {
search+="(?=.*" + words[i] + ")";
}
search = new RegExp(search + ".+", "gi");
}
if(search.test(what)) {
// found
} else {
// notfound
}
I assume you are matching words, or parts of words. You want space-separated search terms to limit search results, and it seems you intend to return only those entries which have all the words that the user supplies. And you intend a wildcard character * to stand for 0 or more characters in a matching word.
For example, if the user searches for the words term1 term2, you intend to return only those items which have both words term1 and term2. If the user searches for the word term*, it would match any word beginning with term.
There are suitable regular expressions which are equivalent to this search language and can be generated from it.
A simple example, the word term, can be asserted in regex by converting to \bterm\b. But two or more words which must match in any order require lookahead assertions. Using extended syntax, the equivalent regex is:
(?= .* \b term1 \b )
(?= .* \b term2 \b )
The asterisk wildcard can be asserted in regex with a character class followed by asterisk. The character class identifies which letters you consider to be part of word. For example, you might find that [A-Za-z0-9]* fits the bill.
In short, you might be satisfied if you convert an expression such as:
foo ba* quux
to:
(?= .* \b foo \b )
(?= .* \b ba[A-Za-z0-9]* \b )
(?= .* \b quux \b )
That is a simple matter of search and replace. But do be careful to sanitize the input string to avoid injection attacks by removing punctuation, etc.
I think you may be barking up the wrong tree with RegEx. What you might want to look at is the Levenshtein distance of two input strings.
There's a Javascript implementation here and a usage example here.
What is the regular expression (in JavaScript if it matters) to only match if the text is an exact match? That is, there should be no extra characters at other end of the string.
For example, if I'm trying to match for abc, then 1abc1, 1abc, and abc1 would not match.
Use the start and end delimiters: ^abc$
It depends. You could
string.match(/^abc$/)
But that would not match the following string: 'the first 3 letters of the alphabet are abc. not abc123'
I think you would want to use \b (word boundaries):
var str = 'the first 3 letters of the alphabet are abc. not abc123';
var pat = /\b(abc)\b/g;
console.log(str.match(pat));
Live example: http://jsfiddle.net/uu5VJ/
If the former solution works for you, I would advise against using it.
That means you may have something like the following:
var strs = ['abc', 'abc1', 'abc2']
for (var i = 0; i < strs.length; i++) {
if (strs[i] == 'abc') {
//do something
}
else {
//do something else
}
}
While you could use
if (str[i].match(/^abc$/g)) {
//do something
}
It would be considerably more resource-intensive. For me, a general rule of thumb is for a simple string comparison use a conditional expression, for a more dynamic pattern use a regular expression.
More on JavaScript regexes: https://developer.mozilla.org/en/JavaScript/Guide/Regular_Expressions
"^" For the begining of the line "$" for the end of it. Eg.:
var re = /^abc$/;
Would match "abc" but not "1abc" or "abc1". You can learn more at https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions
I have an input of type text where I return true or false depending on a list of banned words. Everything works fine. My problem is that I don't know how to check against words with diacritics from the array:
var bannedWords = ["bad", "mad", "testing", "băţ"];
var regex = new RegExp('\\b' + bannedWords.join("\\b|\\b") + '\\b', 'i');
$(function () {
$("input").on("change", function () {
var valid = !regex.test(this.value);
alert(valid);
});
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input type='text' name='word_to_check'>
Now on the word băţ it returns true instead of false for example.
Chiu's comment is right: 'aaáaa'.match(/\b.+?\b/g) yelds quite counter-intuitive [ "aa", "á", "aa" ], because "word character" (\w) in JavaScript regular expressions is just a shorthand for [A-Za-z0-9_] ('case-insensitive-alpha-numeric-and-underscore'), so word boundary (\b) matches any place between chunk of alpha-numerics and any other character. This makes extracting "Unicode words" quite hard.
For non-unicase writing systems it is possible to identify "word character" by its dual nature: ch.toUpperCase() != ch.toLowerCase(), so your altered snippet could look like this:
var bannedWords = ["bad", "mad", "testing", "băţ", "bať"];
var bannedWordsRegex = new RegExp('-' + bannedWords.join("-|-") + '-', 'i');
$(function() {
$("input").on("input", function() {
var invalid = bannedWordsRegex.test(dashPaddedWords(this.value));
$('#log').html(invalid ? 'bad' : 'good');
});
$("input").trigger("input").focus();
function dashPaddedWords(str) {
return '-' + str.replace(/./g, wordCharOrDash) + '-';
};
function wordCharOrDash(ch) {
return isWordChar(ch) ? ch : '-'
};
function isWordChar(ch) {
return ch.toUpperCase() != ch.toLowerCase();
};
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input type='text' name='word_to_check' value="ba">
<p id="log"></p>
Let's see what's going on:
alert("băţ".match(/\w\b/));
This is [ "b" ] because word boundary \b doesn't recognize word characters beyond ASCII. JavaScript's "word characters" are strictly [0-9A-Z_a-z], so aä, pπ, and zƶ match \w\b\W since they contain a word character, a word boundary, and a non-word character.
I think the best you can do is something like this:
var bound = '[^\\w\u00c0-\u02c1\u037f-\u0587\u1e00-\u1ffe]';
var regex = new RegExp('(?:^|' + bound + ')(?:'
+ bannedWords.join('|')
+ ')(?=' + bound + '|$)', 'i');
where bound is a reversed list of all ASCII word characters plus most Latin-esque letters, used with start/end of line markers to approximate an internationalized \b. (The second of which is a zero-width lookahead that better mimics \b and therefore works well with the g regex flag.)
Given ["bad", "mad", "testing", "băţ"], this becomes:
/(?:^|[^\w\u00c0-\u02c1\u037f-\u0587\u1e00-\u1ffe])(?:bad|mad|testing|băţ)(?=[^\w\u00c0-\u02c1\u037f-\u0587\u1e00-\u1ffe]|$)/i
This doesn't need anything like ….join('\\b|\\b')… because there are parentheses around the list (and that would create things like \b(?:hey\b|\byou)\b, which is akin to \bhey\b\b|\b\byou\b, including the nonsensical \b\b – which JavaScript interprets as merely \b).
You can also use var bound = '[\\s!-/:-#[-`{-~]' for a simpler ASCII-only list of acceptable non-word characters. Be careful about that order! The dashes indicate ranges between characters.
You need a Unicode aware word boundary. The easiest way is to use XRegExp package.
Although its \b is still ASCII based, there is a \p{L} (or a shorter pL version) construct that matches any Unicode letter from the BMP plane. To build a custom word boundary using this contruct is easy:
\b word \b
---------------------------------------
| | |
([^\pL0-9_]|^) word (?=[^\pL0-9_]|$)
The leading word boundary can be represented with a (non)capturing group ([^\pL0-9_]|^) that matches (and consumes) either a character other than a Unicode letter from the BMP plane, a digit and _ or a start of the string before the word.
The trailing word boundary can be represented with a positive lookahead (?=[^\pL0-9_]|$) that requires a character other than a Unicode letter from the BMP plane, a digit and _ or the end of string after the word.
See the snippet below that will detect băţ as a banned word, and băţy as an allowed word.
var bannedWords = ["bad", "mad", "testing", "băţ"];
var regex = new XRegExp('(?:^|[^\\pL0-9_])(?:' + bannedWords.join("|") + ')(?=$|[^\\pL0-9_])', 'i');
$(function () {
$("input").on("change", function () {
var valid = !regex.test(this.value);
//alert(valid);
console.log("The word is", valid ? "allowed" : "banned");
});
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/xregexp/3.1.1/xregexp-all.min.js"></script>
<input type='text' name='word_to_check'>
In stead of using word boundary, you could do it with
(?:[^\w\u0080-\u02af]+|^)
to check for start of word, and
(?=[^\w\u0080-\u02af]|$)
to check for the end of it.
The [^\w\u0080-\u02af] matches any characters not (^) being basic Latin word characters - \w - or the Unicode 1_Supplement, Extended-A, Extended-B and Extensions. This include some punctuation, but would get very long to match just letters. It may also have to be extended if other character sets have to be included. See for example Wikipedia.
Since javascript doesn't support look-behinds, the start-of-word test consumes any before mentioned non-word characters, but I don't think that should be a problem. The important thing is that the end-of-word test doesn't.
Also, putting these test outside a non capturing group that alternates the words, makes it significantly more effective.
var bannedWords = ["bad", "mad", "testing", "băţ", "båt", "süß"],
regex = new RegExp('(?:[^\\w\\u00c0-\\u02af]+|^)(?:' + bannedWords.join("|") + ')(?=[^\\w\\u00c0-\\u02af]|$)', 'i');
function myFunction() {
document.getElementById('result').innerHTML = 'Banned = ' + regex.test(document.getElementById('word_to_check').value);
}
<!DOCTYPE html>
<html>
<body>
Enter word: <input type='text' id='word_to_check'>
<button onclick='myFunction()'>Test</button>
<p id='result'></p>
</body>
</html>
When dealing with characters outside my base set (which can show up at any time), I convert them to an appropriate base equivalent (8bit, 16bit, 32bit). before running any character matching over them.
var bannedWords = ["bad", "mad", "testing", "băţ"];
var bannedWordsBits = {};
bannedWords.forEach(function(word){
bannedWordsBits[word] = "";
for (var i = 0; i < word.length; i++){
bannedWordsBits[word] += word.charCodeAt(i).toString(16) + "-";
}
});
var bannedWordsJoin = []
var keys = Object.keys(bannedWordsBits);
keys.forEach(function(key){
bannedWordsJoin.push(bannedWordsBits[key]);
});
var regex = new RegExp(bannedWordsJoin.join("|"), 'i');
function checkword(word) {
var wordBits = "";
for (var i = 0; i < word.length; i++){
wordBits += word.charCodeAt(i).toString(16) + "-";
}
return !regex.test(wordBits);
};
The separator "-" is there to make sure that unique characters don't bleed together creating undesired matches.
Very useful as it brings all the characters down to a common base that everything can interact with. And this can be re-encoded back to it's original without having to ship it in key/value pair.
For me the best thing about it is that I don't have to know all of the rules for all of the character sets that I might intersect with, because I can pull them all into a common playing field.
As a side note:
To speed things up, rather than passing the large regex statement that you probably have, which takes exponentially longer to pass with the length of the words that you're banning, I would pass each separate word in the sentence through the filter. And break the filter up into length based segments. like;
checkword3Chars();
checkword4Chars();
checkword5chars();
who's functions you can generate systematically and even create on the fly as and when they become required.
I'm working on a regex that must match only the text inside quotes but not in a comment, my macthes must only the strings in bold
<"love";>
>/*"love"*/<
<>'love'<>
"lo
more love
ve"
I'm stunck on this:
/(?:((\"|\')(.|\n)*?(\"|\')))(?=(?:\/\**\*\/))/gm
The first one (?:((\"|\')(.|\n)*?(\"|\'))) match all the strings
the second one (?=(?:\/\**\*\/)) doesn't match text inside quotes inside /* "mystring" */
bit my logic is cleary wrong
Any suggestion?
Thanks
Maybe you just need to use a negative lookahead to check for the comment end */?
But first, I'd split the string into separate lines
var arrayOfLines = input_str.split(/\r?\n/);
or, without empty lines:
var arrayOfLines = input_str.match(/[^\r\n]+/g);
and then use this regex:
["']([^'"]+)["'](?!.*\*\/)
Sample code:
var rebuilt_string = ''
var re = /["']([^'"]+)["'](?!.*\*\/)/g;
var subst = '<b>$1</b>';
for (i = 0; i < arrayOfLines.length; i++)
{
rebuilt_string = rebuilt_string + arrayOfLines[i].replace(re, subst) + "\r\n";
}
The way to avoid commented parts is to match them before. The global pattern looks like this:
/(capture parts to avoid)|target/
Then use a callback function for the replacement (when the capture group exists, return the match without change, otherwise, replace the match with what you want.
Example:
var result = text.replace(/(\/\*[^*]*(?:\*+(?!\/)[^*]*)*\*\/)|"[^"\\]*(?:\\[\s\S][^"\\]*)*"|'[^'\\]*(?:\\[\s\S][^'\\]*)*'/g,
function (m, g1) {
if (g1) return g1;
return '<b>' + m + '</b>';
});
I have got a textarea with keyup=validate()
I need a javascript function that gets all words starting with # and ending with a character that is not A-Za-z0-9
For example:
This is a text #user1 this is more text #user2. And this is even more #user3!
The function gives an array:
Array("#user1","#user2","#user3");
I am sure there must be a way to do this written on somewhere on the internet if I just google something but I have no idea what I have to look for.. I am very new with regular expresions.
Thank you very much!
The regular expression you want is:
/#[a-z\d]+/ig
This matches # followed by a sequence of letters and numbers. The i modifier makes it case-insensitive, so you don't have to put A-Z in the character class, and g makes it find all the matches.
var str = "This is a text #user1 this is more text #user2. And this is even more #user3!";
var matches = str.match(/#[a-z\d]+/ig);
console.log(matches);
JS
var str = "This is a text #user1 this is more text #user2. And this is even more #user3!",
var textArr = str.split(" ");
for(var i = 0; i < textArr.length; i++) {
var test = textArr[i];
matches = test.match(/^#.*.[A-Za-z0-9]$/);
console.log(matches);
};
Explanation:
You should also read about the regex(http://www.w3schools.com/jsref/jsref_obj_regexp.asp) and match(http://www.w3schools.com/jsref/jsref_match.asp) to get an idea how it works.
Basically, applying ^# means starting the regex look for #. $ means ending with. and .* any character in between.
To Test: http://www.regular-expressions.info/javascriptexample.html
Thanks for the replies above, they've helped me - Where I've written this method that hopefully answers the question about having a start and end regex check.
In this example it looks for ##_ at the start and _## at the end
e.g. ##_ anyTokenYouNeedToFind _##.
Code:
const tokenSearchHelper = (inputText) => {
let matches = inputText.match(/##_[a-zA-Z0-9_\d]+_##/ig);
return matches;
}
const out = tokenSearchHelper("Hello ##_World_##");
console.log(out);