https://builtin.com/software-engineering-perspectives/javascript-regex
I was working on a secret project ♥️ and required to extract information from the browser’s URL. This is a quick guide on JavaScript regular expressions.
Disclaimer: I have a basic understanding of RegEx and have used them before.
How to Create a Regular Expression in JavaScript
There are two ways to create a regular expression (RegEx) in JavaScript: 1. RegEx Cconstructor (RegExp) 2. RegEx Literal
RegEx Cconstructor (RegExp)
Syntax: new RegExp(pattern[, flags])
Example:
javascript
var regexConst = new RegExp('abc');
RegEx Literal
Syntax: /pattern/flags
Example:
javascript
var regexLiteral = /abc/;
Here, the flags are optional. I will explain these later in this article.
The result is going to be a regex object.
You can to escape the forward slash ( / ) with a backslash ( \ ) if you want to use it as a part of the regex.
RegEx Methods
Regex.prototype.test()
This method is used to test whether a match has been found or not. It accepts a string which we have to test against a regular expression, and it returns true or false depending upon if the match is found or not.
javascript
var regex = /hello/;
var str = 'hello world';
var result = regex.test(str);
console.log(result);
// returns true
Regex.prototype.exec()
This method returns an array containing all the matched groups. It accepts a string that we have to test against a regular expression.
javascript
var regex = /hello/;
var str = 'hello world';
var result = regex.exec(str);
console.log(result);
// returns [ 'hello', index: 0, input: 'hello world', groups: undefined ]
// 'hello' -> is the matched pattern.
// index: -> Is where the regular expression starts.
// input: -> Is the actual string passed.
Bonus: Regex for finding image file in VS Code
/^!\[.*\]\(/
will search for ![...](