How to Replace a Regex Substring Match in JavaScript

How to replace part of a string using regex

You may use a regex that will match the first [....] followed with [ and capture that part into a group (that you will be able to refer to via a backreference), and then match 1+ chars other than ] to replace them with your replacement:

var str = "asd[595442/A][30327][0]";var strToReplace = "30333";console.log(str.replace(/(\[[^\]]*]\[)[^\]]*/, "$1" + strToReplace));
var strDesiredResult = "asd[595442/A][30333][0]";console.log(strDesiredResult);

javascript replace string after matching line

You can use this regex to match your first line:

/(<span id="lastModified">)(.*?)(</span>)/

It basically matches literally the text and captures it in three Groups, which is then used in the replacement pattern, which can be:

$12018-10-26$3

First it replaces with $1 (the first matched Group), then your date (which you will want to come from a variable) and finally $3 which is the end span.

Match and replace by regex, but do replace only for some part found by regexp

Note that you must define \ in a string literal with double \. '[\s.,:\*]+' => '[\\s.,:*]+'. Wrap it with a capturing group and use a backreference in the replacement. RegExp('([\\s.,:*]+)' + word + 's?i?\\s*:?\\s*', 'gi'); and replace with "$1", not "".

var s  = "Some words .testword";var word="testword";var rx = RegExp('([\\s.,:*]+)' +word + 's?i?\\s*:?\\s*', 'gi');console.log(s.replace(rx, "$1"));

String replace with regex by using captured match as key

You can do that with callbacks:

const stringIhave = `<i id="1"></i><i id="2"></i><i id="3"></i>`;
const obj = {  "1": "Red",  "2": "Green",  "3": "Blue"};
const stringIwant = stringIhave.replace(/id="(\d)"/g, (mat, grp) => `color="${obj[grp]}"`);
console.log(stringIwant);

regex replace only a part of the match

var input = "/09/small_image/09x/";var output = input.replace(/(\/\d+\/)small_image\/\d*x/, "$1thumbnail");console.log(output);

JavaScript REGEX Match all and replace

Well, first you'll need the g flag on the regex. This tells JavaScript to replace all matched values. Also you can supply a function to the replace method. Something like this:

var result = str.replace(/\{\{(.*?)\}\}/g, function(match, token) {
    return data[token];
});

The second parameter matches the first subgroup and so on.

Regex: How to replace the matched text with a HTML element in JavaScript?

You could use a capturing group like this:

$1 indicates the text matched within the parentheses (capturing group) and can be used in replace (MDN)

const str = "And here is the {{dog}} which is chasing the {{cat}}"const newStr = str.replace(/{{(\w+)}}/g, "<span class='$1' />")
console.log(newStr)

How to replace words in string by regex pattern with exception

You can use

const regex = /\b(?!google\b)[a-zA-Z0-9]+\.(?:com|net)\b/gi;

Details:

\b - word boundary
(?!google\b) - a negative lookahead that fails the match if there is google as a whole word immediately to the right of the current position
[a-zA-Z0-9]+ - one or more ASCII letters or digits
\. - a dot
(?:com|net) - a non-capturing group matching either com or net
\b - a wor boundary.