JavaScript RegExp
JavaScript RegExp
In JavaScript RegExp is a pattern used to search, match, and manipulate text. It helps validate data like email, phone numbers, passwords, etc.
You can create a RegExp in two ways:
RegExp Methods
test() — Returns true or false
exec() — Returns match details or null
String Methods with RegExp
| Method | Description | Example |
|---|---|---|
match() | Finds matches | "Hello".match(/l/g) |
replace() | Replace matched text | "Hello".replace(/l/g, "*") |
search() | Returns first match index | "Hello".search(/e/) |
split() | Split using regex | "a,b;c".split(/[,;]/) |
Example:
RegExp Modifiers (Flags)
| Flag | Meaning | Example |
|---|---|---|
g | Global search | /a/g |
i | Case-insensitive | /apple/i |
m | Multi-line | /^hello/m |
Example:
RegExp Special Characters
| Symbol | Meaning | Example |
|---|---|---|
. | Any character | /h.t/ → “hat”, “hot” |
^ | Begins with | /^hello/ |
$ | Ends with | /world$/ |
\d | Digits 0–9 | /\d/ |
\w | Alphanumeric | /\w/ |
\s | Whitespace | /\s/ |
+ | One or more | /a+/ |
* | Zero or more | /a*/ |
{n} | Exact count | /\d{3}/ → 3 digits |
| ` | ` | OR |
Useful Examples
Validate Email
Validate Phone Number (Indian Example)
Strong Password Check
Summary
| Feature | Example |
|---|---|
| Create RegExp | /pattern/ |
| Test text | regex.test(text) |
| Search & replace | text.replace(regex, value) |
| Validate input | Emails, phone numbers, passwords |
