javascript string match regex - Brave Search

Check whether a string matches a regex in JS

stackoverflow.com › questions › 6603015 › check-whether-a-string-matches-a-regex-in-js

Use regex.test() if all you want is a boolean result:

console.log(/^([a-z0-9]{5,})$/.test('abc1')); // false

console.log(/^([a-z0-9]{5,})$/.test('abc12')); // true

console.log(/^([a-z0-9]{5,})$/.test('abc123')); // true

...and you could remove the () from your regexp since you've no need for a capture.

Answer from user113716 on Stack Overflow

w3schools.com › jsref › jsref_match.asp

JavaScript String match() Method

The search() method returns the position of the first match. ... Regular Expression Search and Replace can be done with different methods. ... If you want to use W3Schools services as an educational institution, team or enterprise, send us an e-mail: sales@w3schools.com · If you want to report an error, or if you want to make a suggestion, send us an e-mail: help@w3schools.com · HTML Tutorial CSS Tutorial JavaScript Tutorial How To Tutorial SQL Tutorial Python Tutorial W3.CSS Tutorial Bootstrap Tutorial PHP Tutorial Java Tutorial C++ Tutorial jQuery Tutorial

stackoverflow.com › questions › 6603015 › check-whether-a-string-matches-a-regex-in-js

javascript - Check whether a string matches a regex in JS - Stack Overflow

Use regex.test() if all you want is a boolean result:

console.log(/^([a-z0-9]{5,})$/.test('abc1')); // false

console.log(/^([a-z0-9]{5,})$/.test('abc12')); // true

console.log(/^([a-z0-9]{5,})$/.test('abc123')); // true

...and you could remove the () from your regexp since you've no need for a capture.

Use test() method :

var term = "sample1";
var re = new RegExp("^([a-z0-9]{5,})$");
if (re.test(term)) {
    console.log("Valid");
} else {
    console.log("Invalid");
}

Discussions

Regular Expressions test() - match()? Are these used interchangeably?

Jonathan Grieve is having issues with: Just a quick question to help clear up some confusion. Joel mentions the match() method but seems to use the test() method in its place.... More on teamtreehouse.com

teamtreehouse.com

1

September 4, 2017

[Javascript]String match with regex gives weird results

Read through the description section of https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/match - essentially .match() behaves differently if you use the /g flag. Also your use of ";?" at the end of the regex won't do anything, the "(.+)" before it will greedily match to the end of the string. I'm curious what you're trying to do here, and why we're parsing JavaScript commands in a regular expression in the first place. More on reddit.com

r/learnprogramming

7

2

October 12, 2015

Regexp match only integers, ignore floats and other characters.

str.split(",").filter(x => Number.isInteger(Number(x)));

Should be faster than regex.

*Edited to include cast to Number since isInteger is false for strings

More on reddit.com

r/javascript

12

7

April 17, 2015

Regex- How to Match Parentheses

Something like this? https://regex101.com/r/rH0zB0/1 More on reddit.com

r/javascript

4

1

July 18, 2016

Videos

An Easy Way to Do Regex - JavaScript String Match (In 2 Mins)

How to use regex to check if a javascript string contains a pattern ...

September 12, 2022

JavaScript Regex Tutorial: Mastering the match() Method for Pattern ...

September 6, 2025

Regular Expressions (Regex) in JavaScript - tutorial - YouTube

JavaScript Regular Expressions: Match Beginning String Patterns ...

September 21, 2023

RegExp - regex // JavaScript Regular Expressions Ultimate MasterClass ...

February 12, 2024

freecodecamp.org › news › javascript-regex-match-example-how-to-use-the-js-replace-method-on-a-string

JavaScript Regex Match Example – How to Use JS Replace on a String

January 4, 2021 - In this case, we .match() an array with the first match along with the index of the match in the original string, the original string itself, and any matching groups that were used. But say you want to see how many times the word "are" occurs in a string. To do that, just add the global search flag to your regular expression: const csLewisQuote = 'We are what we believe we are.'; const regex = /are/g; csLewisQuote.match(regex); // ["are", "are"]

sitepoint.com › blog › javascript › quick tip: testing if a string matches a regex in javascript

Quick Tip: Testing if a String Matches a Regex in JavaScript — SitePoint

November 6, 2024 - This method accepts a string as a parameter and returns a Boolean value indicating whether the string matches the regular expression. Regular expressions in JavaScript are beneficial for detecting information in a string that can be written ...

medium.com › nerd-for-tech › basics-of-javascript-string-match-method-ce47295bfd97

Basics of Javascript · String · match() (method) | by Jakub Korch | Nerd For Tech | Medium

June 9, 2021 - That's...", // length: 0 // ]regExp.exec(str) // [ // "ain", // groups: undefined, // index: 5, // input: "The main bulk of rain will fall in SPAIN. That's...", // length: 0 // ](str.match(regExp))[0] // ain · First case uses regular expressions searching for the string “ain” with the additional flag “g” which specifies that we want to find all the matches.

codingnomads.com › match-string-javascript

JavaScript String Matching

The first one uses the forward slash notation, and the second one uses the RegExp constructor. The second one is a bit more complicated, though, because you need to escape the backslashes. This is because the backslash is a special character in JavaScript strings, so you need to escape it with another backslash. You can also pass a normal string to the .search() and .match() methods where it will get automatically converted into a RegExp object.

honeybadger.io › blog › javascript-regular-expressions

The ultimate JavaScript regex guide - Honeybadger Developer Blog

May 9, 2025 - The code above creates a simple regex pattern that will result in a JavaScript regex match for the first occurrence of the exact text "Hello". This notation is used when you know how the pattern will look when writing the code. Note: You don't need to enclose the patterns in single or double quotes; you can add flags after the closing forward slash. JavaScript has a RegExp constructor that you can use to create regex patterns. You pass the pattern as a string argument to the constructor:

Find elsewhere

Google Bing Mojeek

teamtreehouse.com › community › regular-expressions-test-match-are-these-used-interchangeably

Regular Expressions test() - match()? Are these used interchangeably? (Example) | Treehouse Community

The test() method executes a search for a match between a regular expression and a specified string. Returns true or false. The match() method retrieves the matches when matching a string against a regular expression. Use .test if you want a faster boolean check. Use .match to retrieve all matches when using the g global flag. Enjoy! REFERENCES http://devdocs.io/javascript/globalobjects/string/match

carmatec.com › home › guide to mastering javascript regex match with examples

Guide to Mastering JavaScript Regex Match with Examples

December 31, 2025 - They are appended after the closing ... search (find all matches, not just the first). ... The test() method checks if a string matches the regex pattern and returns a boolean....

reddit.com › r/learnprogramming › [javascript]string match with regex gives weird results

r/learnprogramming on Reddit: [Javascript]String match with regex gives weird results

October 12, 2015 -

As I understand it, .match is supposed to return only matched groups, and would be the thing to use for "global" matches, so I'm doing just that to get variable names and their definitions from the code of a function. However...

var str = "function startMidiMusic(s) {	popBox = window.open(s,'midi','scrollbars=no,resizable=no,width=250,height=125,left=10,top=10');	popBox.focus();	foo = 'bar';}";

//Gets an extraneous thing and only the first result
str.match(/(\S+) ?= ?(.+);?/);
>> Array [ "popBox = window.open(s,'midi','scro…", "popBox", "window.open(s,'midi','scrollbars=no…" ]

//Only gets a portion of the "original" string
str.match(/(\S+) ?= ?(.+);?/g);
>> Array [ "popBox = window.open(s,'midi','scro…" ]

None of them include "foo" and "bar", let alone in the way I'm expecting

What's going on?

Read through the description section of https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/match - essentially .match() behaves differently if you use the /g flag. Also your use of ";?" at the end of the regex won't do anything, the "(.+)" before it will greedily match to the end of the string. I'm curious what you're trying to do here, and why we're parsing JavaScript commands in a regular expression in the first place.

Well, the first thing of note is that your regex doesn't quite seem correct. Assuming you wanted to capture the name of the variable being assigned to and the value it's given, we can't use .+, since that would consume the ; that marks the end of the value (and thus we'd end up consuming too much) Instead, we'd have to use a group containing all valid characters we'd want to consume (which is pretty much everything not a ;). /(\S+) ?= ?([^;]+);?/ An alternative would be to use lazy matching for something that must end with a semicolon: /(\S+) ?= ?(.+?;)/ The laziness there is crucial. It ensures it tries to match as little as possible, and thus stops matching at that first semicolon. Of course, both approaches still fail if there's a semicolon inside a string. You can't parse JS with regex! But I'll assume you're aware of this limitation and are okay with the approximate results. In this case, the returned value is: The match made: "popBox = window.open(s,'midi','scrollbars=no,resizable=no,width=250,height=125,left=10,top=10');" The two capture groups: "popBox" and ""window.open(s,'midi','scrollbars=no,resizable=no,width=250,height=125,left=10,top=10')". In case it wasn't obvious, the … is the browser's console truncating a long string. Access the array element itself to see the full string. That's presumably why you think you're only getting a portion of the original string. You actually got it all, but it wasn't all shown.

developer.mozilla.org › en-US › docs › Web › JavaScript › Reference › Global_Objects › String › match

String.prototype.match() - JavaScript | MDN

The match() method of String values retrieves the result of matching this string against a regular expression. const paragraph = "The quick brown fox jumps over the lazy dog. It barked."; const regex = /[A-Z]/g; const found = paragraph.match(regex); console.log(found); // Expected output: Array ...

JavaScript.info

javascript.info › tutorial › regular expressions

Methods of RegExp and String

July 13, 2022 - The method str.match(regexp) finds matches for regexp in the string str.

developer.mozilla.org › en-US › docs › Web › JavaScript › Guide › Regular_expressions

Regular expressions - JavaScript | MDN

For instance, to match the string "C:\" where "C" can be any letter, you'd use /[A-Z]:\\/ — the first backslash escapes the one after it, so the expression searches for a single literal backslash. If using the RegExp constructor with a string literal, remember that the backslash is an escape ...

geeksforgeeks.org › javascript › how-to-match-multiple-parts-of-a-string-using-regexp-in-javascript

JavaScript - How to Match Multiple Parts of a String Using RegExp? - GeeksforGeeks

July 23, 2025 - Non-capturing groups (?:...) allow you to combine multiple patterns without creating separate capturing groups. This is useful when you need to match multiple patterns in a string but don’t need to extract the individual parts. ... let s = "apple123 orange456 apple789"; let regex = /(?:apple|orange)\d+/g; let res = s.match(regex); console.log(res);

w3schools.com › js › js_regexp.asp

JavaScript Regular Expressions

JavaScript RegExp is an Object for handling Regular Expressions. ... let text = "Visit Microsoft!"; let result = text.replace(/Microsoft/i, "W3Schools"); Try it Yourself » ... In a regular expression an alternation is denoted with a vertical line character |. An alternation matches any of the ...

developer.mozilla.org › en-US › docs › Web › JavaScript › Reference › Global_Objects › RegExp › test

RegExp.prototype.test() - JavaScript | MDN

Using this internally, test() can be used to iterate over multiple matches in a string of text (with capture groups). const str = "table football"; const regex = /fo+/; const globalRegex = /fo+/g; console.log(regex.test(str)); // Expected output: true console.log(globalRegex.lastIndex); // Expected output: 0 console.log(globalRegex.test(str)); // Expected output: true console.log(globalRegex.lastIndex); // Expected output: 9 console.log(globalRegex.test(str)); // Expected output: false

medium.com › codex › using-regular-expressions-in-javascript-edcd5942de89

Using Regular Expressions in JavaScript | by Wesley Beck | CodeX | Medium

June 24, 2021 - The .test() operation returns a ... Rather than returning a Boolean value, .match() will actually return the part of the string that exactly matches your regular expression created....

RegExr: Learn, Build, & Test RegEx

Supports JavaScript & PHP/PCRE RegEx. Results update in real-time as you type. Roll over a match or expression for details.

regex101: build, test, and debug regex

Regular expression tester with syntax highlighting, explanation, cheat sheet for PHP/PCRE, Python, GO, JavaScript, Java, C#/.NET, Rust.

Eloquent JavaScript

eloquentjavascript.net › 09_regexp.html

Regular Expressions :: Eloquent JavaScript

This code takes a string, finds all occurrences of a number followed by an alphanumeric word, and returns a string that has one less of every such quantity. The (\d+) group ends up as the amount argument to the function, and the (\p{L}+) group gets bound to unit. The function converts amount to a number—which always works, since it matched \d+ earlier—and makes some adjustments in case there is only one or zero left. We can use replace to write a function that removes all comments from a piece of JavaScript code.