Develop Reference

From 'one behind' to 'one before' (between)

In the string below, I want to find, for example, everything between '[' and 'A'.
Here 'match1', 'match2', 'match3'. And than replace every match with, for example, 'check'.
var str = "+dkdele*[match1Ayesses ss [match2Aevey[match3A";
var pattern = /(?=\[)(.*?)([]?A)/g; // includes '[' and 'A'
var res = str.replace(pattern, "check"); // could be '[checkA'
console.log(res);
The pattern includes '[' and 'A', what I don't want. How could a pattern look like, which matches between two any desired signs?

You can use this regex:
/\[(\w+)(?=A)/g
and grab captured group #1
RegEx Demo
If there can be more than word characters then use:
/\[([^A]+)(?=A)/g
Code:
var re = /\[([^A]+)(?=A)/g;
var str = '+dkdele*[match1Ayesses ss [match2Aevey[match3A';
var m;
while ((m = re.exec(str)) !== null) {
if (m.index === re.lastIndex)
re.lastIndex++;
console.log(m[1]);
}
Output:
match1
match2
match3
EDIT: Based on edited question and comment below:
For replacement you can use:
var repl = str.replace(/(\[)[^A]+(?=A)/, '$1check');
//=> +dkdele*[checkAyesses ss [checkAevey[checkA
PS: If you want A also to be replaced then use:
var repl = str.replace(/(\[)[^A]+A/, '$1check');
//=> +dkdele*[checkyesses ss [checkevey[check

You can use:
var pattern = /(\[).*?(A)/g;
var replacement = "check";
var res = str.replace( pattern, '$1' + replacement + '$2' );
The regular expression is:
(\[) - match an open square bracket and capture the match in a the first group.
.*? - match the minimum possible of zero-or-more of any characters
(A) - then match an A and capture it in the second group.
The replacement will put in the first and second capture groups instead of $1 and $2 (respectively).
With any start and end matches you can do:
var start = "\\[";
var end = "A";
var pattern = new RegExp( "(" + start + ").*?(" + end + ")", "g" );
var replacement = "check";
var res = str.replace( pattern, '$1' + replacement + '$2' );
If you don't want to include the start and end match characters then don't include the capture groups in the replacement:
var res = str.replace( pattern, replacement );

How do I escape a string used in a RegExp object

I have the following bit of code :
var stringToMatch = "De$mond. \(blah)";
var pattern = "^" + stringToMatch;
var regex = new RegExp(pattern, "i");
return regex.test("testing De$mond.");
Now I need to escape stringToMatch before using it in pattern
A solution I found here suggest this method if I understand correctly :
var stringToMatch = "De$mond. \(blah)";
stringToMatch = stringToMatch.replace(/[\-\[\]\/\{\}\(\)\*\+\?\.\\\^\$\|]/g, "\\$&");
var pattern = "^" + stringToMatch;
var regex = new RegExp(pattern, "i");
return regex.test("testing De$mond.");
Why can't I simply escape all of the characters in stringToMatch instead?
e.g.
var stringToMatch = "De$mond. \(blah)";
var stringToMatchAsArrayOfChars = [];
for (var i = 0; i < stringToMatch.length; i++)
{
stringToMatchAsArrayOfChars.push(stringToMatch.substr(i, 1));
}
var stringToMatchEscaped = "";
for (var i = 0; i < stringToMatchAsArrayOfChars.length; i++)
{
if (stringToMatchAsArrayOfChars[i] !== " ")
{
stringToMatchEscaped = stringToMatchEscaped + "\\" + stringToMatchAsArrayOfChars[i];
}
else
{
stringToMatchEscaped = stringToMatchEscaped + " ";
}
}
var pattern = "^" + stringToMatch;
var regex = new RegExp(pattern, "i");
return regex.test("testing De$mond.");
I understand that the above method is much more verbose but what it basically does is :
var stringToMatchEscaped = "\D\e\$\m\o\n\d\. \\\(\b\l\a\h\)";
But it's not working. Why is that?
And, also, is there some other way of escaping stringToMatch other than the one suggested in the link I provided? i.e. without specifying which characters to escape like it's being dones with /[\-\[\]\/\{\}\(\)\*\+\?\.\\\^\$\|]/g ?

here is a simple regexp to make safe regexp patterns from string input.
var pattern= "De$mond.";
var regex = new RegExp(pattern.replace( /([.*+?^${}()|[\]\/\\])/g , '\\$1'), "i");
regex.test("testing De$mond. string here."); // === true
note that this means you cannot use the "wildcards" or any RegExp syntax, but you'll end up with a real regexp that will perform a literal match from the source text to the pattern.

regex restriction alphabet

I have a string as :
var str = "str is str, 12str345 and ABCstrDEF";
I want capture all str except ABCstrDEF (str surrounded by alphabetical characters)
Is it possible restrict alphabets with regex?

Go with
RegExp.quote = function(str) {
return (str + '').replace(/([.?*+^$[\]\\(){}|-])/g, "\\$1");
};
var re = new RegExp("/\b[^a-zA-Z]*?" + RegExp.quote(str) + "[^a-zA-Z]*?\b/g");
alert(input.match(re));

JS .replace place b tag in string where == string [duplicate]

This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
Case insensitive string replacement in JavaScript?
I am trying to highlight part of a string where it is equal to another variable value.
For example
var string = 'This Is A Test String';
var findWord = 'test';
result should be
'This Is A <b>Test</b> String'
Please note the case insensitive and that I require the use of using variables to pass the 'find/Replace word'
reason I need to do it this was is to keep the exact form/case of the string found where is == to the search word.
In PHP, this works, so basically I'm after the JS equivalent of
preg_replace('/('.$search.')/i','<b>$1</b>',$val['name'])
I'm not good when it comes to regex, this should be simple for someone.

I'd suggest:
var string = "This is a test string.",
needle = "test",
re = new RegExp(needle, "gi"),
newString = string.replace(re, "<strong>" + needle + "</strong>");
console.log(newString);
JS Fiddle demo.
Note that I used <strong></strong> rather than <b></b> (deliberately), though, of course, you can use whatever element-type you like. Also, the gi flags:
g is for a global search, rather than simply stopping at the first match, and
i is for case-insensitive, so 'test' will match Test,tESt and so on...
Edited to preserve capitalization of the matched string/substring:
var string = "This is a Test string.",
needle = "test",
re = new RegExp(needle, "gi"),
newString = string.replace(re, function(a,b){
return "<strong>" + a + "</strong>";
});
document.getElementById('input').appendChild(document.createTextNode(string));
document.getElementById('result').innerHTML = newString;
JS Fiddle demo.
Edited to create a more functional/reusable approach:
function formatMatches(el, needle, wrapper) {
if (!el || !needle) {
return false;
}
else {
var re = new RegExp(needle, "gi"),
haystack = el.textContent,
o = '<' + wrapper + '>',
c = '</' + wrapper + '>';
return haystack.replace(re, function(a) {
return o + a + c;
});
}
}
var needle = "test",
el = document.getElementById('input'),
wrapper = 'strong';
document.getElementById('result').innerHTML = formatMatches(el, needle, wrapper);
JS Fiddle demo.
References:
node.appendChild().
document.createTextNode().
RegExp().
string.replace().

var str = 'This Is A Test String';
var w = 'test';
var result = str.replace(new RegExp(w, 'gi'), function(match) {
return "<b>" + match + "</b>";
});
EDIT: Or, as suggested by the comment, the last line could be replaced by:
var result = str.replace(new RegExp(w, 'gi'), "<b>$&</b>");

generic regexp using jquery variable to replace dot, colon or any other character

I have a jquery code that trims the leading and trailing character (passed from the calling program). I am using a variable in RegExp to replace the character with blank. How can I make the RegExp work for any character passed from the calling program? Here is the simplified code:
var time = ":1h:45m:34s:";
var chr= ':'; //can have . or , or any other character
var regex = new RegExp("(^" + chr + ")|(" + chr+ "$)" , "g"); //works for colon but not for dot.
//var regex = new RegExp("(^/" + chr + ")|(/" + chr+ "$)" , "g"); //for dot I added / but not for colon.
var formattedtime = time.replace(regex, "");
Expected Outputs:
1. time = ":1h:45m:34s:";
chr = ":";
Output: 1h:45m:34s
2. time = "1h:45m:34s";
chr = ":";
Output: 1h:45m:34s
3. time = ".45m.34s";
chr = ".";
Output: 45m.34s
4. time = "1h.45m.34s.";
chr = ".";
Output: 1h.45m.34s
How can I make the regexp work for any character?

You need to escape meta characters (like . and several others) to get literals. You do that by adding a backslash before them.
JS doesn't have any built in function for that, so you could use this:
function quotemeta(str){
return str.replace(/[.+*?|\\^$(){}\[\]-]/g, '\\$&');
}
Used like so:
new RegExp("^(?:" + quotemeta(chr) + ")+|(?:" + quotemeta(chr) + ")+$" , "g");

var chr= ':/';
...
var regex = new RegExp("(^[" + chr + "])|([" + chr+ "]$)" , "g");

Regex should this way:-
For Colon, /^(\:)|(\:)$/gim
For Dot, /^(\.)|(\.)$/gim
OR
/^(\:|\w|\.)|(\:|\w|\.)$/gim
LIVE DEMO