Hi all I tried to create some regex with random value.
var data = "demo purpose?"; **OR** var data = "demo purpose";
var sentence = "can I put these app as demo purpose?";
var re = new RegExp("\\b(" + data + ")\\b", "g");
console.log(sentence.match(re)); // output ["demo purpose"]
In variable data have two different value demo purpose? & demo purpose with only question mark. Both console out are same please any one Give me hint what should i do in these case.
-
Thank you
you need to escape ? (i.e. write \\?) or else it would be interpreted as a quantifier in regex.
Furthermore, the \\b is not really necessary because it tries to match a non blank char in which case there is nothing behind demo purpose? so sentence.match(new RegExp("\\b(demo purpose\\?)\\b", "g")) would return null.
If you want randomness, use Math.random. Make an array and get an random integer or 0 or 1 (with Math.floor) as the index.
In order to pass variables into JS regex when using constructor notation, you need to escape all characters that act as regex special characters (quantifiers, group delimiters, etc.).
The escape function is available at MDN Web site:
function escapeRegExp(string){
return string.replace(/[.*+?^${}()|[\]\\]/g, "\\$&");
}
Note also, that \b is a word boundary, and it prevents from matching the strings you need as ? is a non-word character. If you do not need to match word boundaries, remove \b. If you need to check if the search word is a whole word, use (?:^|\W) at the beginning and (?!\w) at the end and use exec rather than match to obtain access to the captured group 1.
So, your code will become:
function escapeRegExp(string){
return string.replace(/[.*+?^${}()|[\]\\]/g, "\\$&");
}
var data = "demo purpose?";
var sentence = "can I put these app as demo purpose?";
var re = new RegExp("(?:^|\\W)(" + escapeRegExp(data) + ")(?!\\w)", "g");
while ((m = re.exec(sentence)) !== null) {
console.log(m[1]); // output ["demo purpose?"]
}
If you search for emo purpose?, no result will be returned since there will be no match.
This
var data = "demo purpose?"; // **OR** var data = "demo purpose";
var sentence = "can I put these app as demo purpose?";
var re = new RegExp(/demo purpose\?/, "g");
console.log(sentence.match(re)); // output ["demo purpose?"]
return ["demo purpose?"],
changing RegExp("xxx", "g"); to RegExp(/xxx/, "g");
You can do
var data = /demo purpose\?/; // **OR** var data = "demo purpose";
var sentence = "can I put these app as demo purpose?";
var re = new RegExp(data, "g");
console.log(sentence.match(re));
and you will get the same output
Related
I am trying to create a regular expression in JS which will match the occurences of box and return the full compound word
Using the string:
the box which is contained within a box-wrap has a box-button
I would like to get:
[box, box-wrap, box-button]
Is this possible to match these words only using the string box?
This is what I have tried so far but it does not return the results I desire.
http://jsfiddle.net/w860xdme/
var str ='the box which is contained within a box-wrap has a box-button';
var regex = new RegExp('([\w-]*box[\w-]*)', 'g');
document.getElementById('output').innerHTML=str.match(regex);
Try this way:
([\w-]*box[\w-]*)
Regex live here.
Requested by comments, here is a working example in javascript:
function my_search(word, sentence) {
var pattern = new RegExp("([\\w-]*" + word + "[\\w-]*)", "gi");
sentence.replace(pattern, function(match) {
document.write(match + "<br>"); // here you can do what do you want
return match;
});
};
var phrase = "the box which is contained within a box-wrap " +
"has a box-button. it is inbox...";
my_search("box", phrase);
Hope it helps.
I'll just throw this out there:
(box[\w-]*)+
You can use this regex in JS:
var w = "box"
var re = new RegExp("\\b" + w + "\\S*");
RegEx Demo
This should work, note the 'W' is upper case.
http://www.w3schools.com/jsref/jsref_obj_regexp.asp
\Wbox\W
It looks like you're wanting to use the match with a regex. Match is a string method that will take a regex as an argument and return an array containing matches.
var str = "your string that contains all of the words you're looking for";
var regex = /you(\S)*(?=\s)/g;
var returnedArray = str.match(regex);
//console.log(returnedArray) returns ['you', 'you\'re']
I'm having trouble trying to use multiple back references in a javascript match so far I've got: -
function newIlluminate() {
var string = "the time is a quarter to two";
var param = "time";
var re = new RegExp("(" + param + ")", "i");
var test = new RegExp("(time)(quarter)(the)", "i");
var matches = string.match(test);
$("#debug").text(matches[1]);
}
newIlluminate();
#Debug when matching the Regex 're' prints 'time' which is the value of param.
I've seen match examples where multiple back references are used by wrapping the match in parenthesis however my match for (time)(quarter)... is returning null.
Where am I going wrong? Any help would be greatly appreciated!
Your regex is literally looking for timequarterthe and splitting the match (if it finds one) into the three backreferences.
I think you mean this:
var test = /time|quarter|the/ig;
Your regex test simply doesn't match the string (as it does not contain the substring timequarterthe). I guess you want alternation:
var test = /time|quarter|the/ig; // does not even need a capturing group
var matches = string.match(test);
$("#debug").text(matches!=null ? matches.join(", ") : "did not match");
I want to add a (variable) tag to values with regex, the pattern works fine with PHP but I have troubles implementing it into JavaScript.
The pattern is (value is the variable):
/(?!(?:[^<]+>|[^>]+<\/a>))\b(value)\b/is
I escaped the backslashes:
var str = $("#div").html();
var regex = "/(?!(?:[^<]+>|[^>]+<\\/a>))\\b(" + value + ")\\b/is";
$("#div").html(str.replace(regex, "" + value + ""));
But this seem not to be right, I logged the pattern and its exactly what it should be.
Any ideas?
To create the regex from a string, you have to use JavaScript's RegExp object.
If you also want to match/replace more than one time, then you must add the g (global match) flag. Here's an example:
var stringToGoIntoTheRegex = "abc";
var regex = new RegExp("#" + stringToGoIntoTheRegex + "#", "g");
// at this point, the line above is the same as: var regex = /#abc#/g;
var input = "Hello this is #abc# some #abc# stuff.";
var output = input.replace(regex, "!!");
alert(output); // Hello this is !! some !! stuff.
JSFiddle demo here.
In the general case, escape the string before using as regex:
Not every string is a valid regex, though: there are some speciall characters, like ( or [. To work around this issue, simply escape the string before turning it into a regex. A utility function for that goes in the sample below:
function escapeRegExp(stringToGoIntoTheRegex) {
return stringToGoIntoTheRegex.replace(/[-\/\\^$*+?.()|[\]{}]/g, '\\$&');
}
var stringToGoIntoTheRegex = escapeRegExp("abc"); // this is the only change from above
var regex = new RegExp("#" + stringToGoIntoTheRegex + "#", "g");
// at this point, the line above is the same as: var regex = /#abc#/g;
var input = "Hello this is #abc# some #abc# stuff.";
var output = input.replace(regex, "!!");
alert(output); // Hello this is !! some !! stuff.
JSFiddle demo here.
Note: the regex in the question uses the s modifier, which didn't exist at the time of the question, but does exist -- a s (dotall) flag/modifier in JavaScript -- today.
If you are trying to use a variable value in the expression, you must use the RegExp "constructor".
var regex = "(?!(?:[^<]+>|[^>]+<\/a>))\b(" + value + ")\b";
new RegExp(regex, "is")
I found I had to double slash the \b to get it working. For example to remove "1x" words from a string using a variable, I needed to use:
str = "1x";
var regex = new RegExp("\\b"+str+"\\b","g"); // same as inv.replace(/\b1x\b/g, "")
inv=inv.replace(regex, "");
You don't need the " to define a regular expression so just:
var regex = /(?!(?:[^<]+>|[^>]+<\/a>))\b(value)\b/is; // this is valid syntax
If value is a variable and you want a dynamic regular expression then you can't use this notation; use the alternative notation.
String.replace also accepts strings as input, so you can do "fox".replace("fox", "bear");
Alternative:
var regex = new RegExp("/(?!(?:[^<]+>|[^>]+<\/a>))\b(value)\b/", "is");
var regex = new RegExp("/(?!(?:[^<]+>|[^>]+<\/a>))\b(" + value + ")\b/", "is");
var regex = new RegExp("/(?!(?:[^<]+>|[^>]+<\/a>))\b(.*?)\b/", "is");
Keep in mind that if value contains regular expressions characters like (, [ and ? you will need to escape them.
I found this thread useful - so I thought I would add the answer to my own problem.
I wanted to edit a database configuration file (datastax cassandra) from a node application in javascript and for one of the settings in the file I needed to match on a string and then replace the line following it.
This was my solution.
dse_cassandra_yaml='/etc/dse/cassandra/cassandra.yaml'
// a) find the searchString and grab all text on the following line to it
// b) replace all next line text with a newString supplied to function
// note - leaves searchString text untouched
function replaceStringNextLine(file, searchString, newString) {
fs.readFile(file, 'utf-8', function(err, data){
if (err) throw err;
// need to use double escape '\\' when putting regex in strings !
var re = "\\s+(\\-\\s(.*)?)(?:\\s|$)";
var myRegExp = new RegExp(searchString + re, "g");
var match = myRegExp.exec(data);
var replaceThis = match[1];
var writeString = data.replace(replaceThis, newString);
fs.writeFile(file, writeString, 'utf-8', function (err) {
if (err) throw err;
console.log(file + ' updated');
});
});
}
searchString = "data_file_directories:"
newString = "- /mnt/cassandra/data"
replaceStringNextLine(dse_cassandra_yaml, searchString, newString );
After running, it will change the existing data directory setting to the new one:
config file before:
data_file_directories:
- /var/lib/cassandra/data
config file after:
data_file_directories:
- /mnt/cassandra/data
Much easier way: use template literals.
var variable = 'foo'
var expression = `.*${variable}.*`
var re = new RegExp(expression, 'g')
re.test('fdjklsffoodjkslfd') // true
re.test('fdjklsfdjkslfd') // false
Using string variable(s) content as part of a more complex composed regex expression (es6|ts)
This example will replace all urls using my-domain.com to my-other-domain (both are variables).
You can do dynamic regexs by combining string values and other regex expressions within a raw string template. Using String.raw will prevent javascript from escaping any character within your string values.
// Strings with some data
const domainStr = 'my-domain.com'
const newDomain = 'my-other-domain.com'
// Make sure your string is regex friendly
// This will replace dots for '\'.
const regexUrl = /\./gm;
const substr = `\\\.`;
const domain = domainStr.replace(regexUrl, substr);
// domain is a regex friendly string: 'my-domain\.com'
console.log('Regex expresion for domain', domain)
// HERE!!! You can 'assemble a complex regex using string pieces.
const re = new RegExp( String.raw `([\'|\"]https:\/\/)(${domain})(\S+[\'|\"])`, 'gm');
// now I'll use the regex expression groups to replace the domain
const domainSubst = `$1${newDomain}$3`;
// const page contains all the html text
const result = page.replace(re, domainSubst);
note: Don't forget to use regex101.com to create, test and export REGEX code.
var string = "Hi welcome to stack overflow"
var toSearch = "stack"
//case insensitive search
var result = string.search(new RegExp(toSearch, "i")) > 0 ? 'Matched' : 'notMatched'
https://jsfiddle.net/9f0mb6Lz/
Hope this helps
Need to replace a substring in URL (technically just a string) with javascript.
The string like
http://blah-blah.com/search?par_one=test&par_two=anothertest&SearchableText=TO_REPLACE
or
http://blah-blah.com/search?par_one=test&SearchableText=TO_REPLACE&par_two=anothertest
means, the word to replace can be either at the most end of the URL or in the middle of it.
I am trying to cover these with the following:
var newWord = NEW_SEARCH_TERM;
var str = 'http://blah-blah.com/search?par_one=test&SearchableText=TO_REPLACE&par_two=anothertest';
var regex = /^\S+SearchableText=(.*)&?\S*$/;
str = str.replace(regex, newWord);
But no matter what I do I get str = NEW_SEARCH_TERM. Moreover the regular expression when I try it in RegExhibit, selects the word to replace and everything that follows it that is not what I want.
How can I write a universal expression to cover both cases and make the correct string be saved in the variable?
str.replace(/SearchableText=[^&]*/, 'SearchableText=' + newWord)
The \S+ and \S* in your regex match all non-whitespace characters.
You probably want to remove them and the anchors.
http://jsfiddle.net/mplungjan/ZGbsY/
ClyFish did it while I was fiddling
var url1="http://blah-blah.com/search?par_one=test&par_two=anothertest&SearchableText=TO_REPLACE";
var url2 ="http://blah-blah.com/search?par_one=test&SearchableText=TO_REPLACE&par_two=anothertest"
var newWord = "foo";
function replaceSearch(str,newWord) {
var regex = /SearchableText=[^&]*/;
return str.replace(regex, "SearchableText="+newWord);
}
document.write(replaceSearch(url1,newWord))
document.write('<hr>');
document.write(replaceSearch(url2,newWord))
I'm trying to create a Regex with jQuery so it will search for two words in an attribute of an XML file.
Can someone tell me how to return a result that contains BOTH words (sport and favorite) in any order and any case (upper or lower case)?
var regex = new RegExp("sport favorite", 'i');
var $result = $(data).filter(function() {
if($(this).attr('Description')) {
return $(this).attr('Description').match(regex);
}
});
If they may be separated by any character, you could do it like this:
var regex = new RegExp(".*sport.+favorite.*|.*favorite.+sport.*", 'i');
(This assumes that no other word in the attribute contains the substring favorite or sport.)
var regex = new RegExp("sport favorite|favorite sport", 'i');
The "\b" marker can be used to "match" the edges of words, so
var regex = /\bsport\b.*\bfavorite\b|\bfavorite\b.*\bsport\b/i;
matches the words only as words, and (for example) won't match "sporting his favorite hat".