RegExp

Tools for working with JavaScript regular expressions from the Effect module namespace. The module exposes the native RegExp constructor, a guard for narrowing unknown values, and escaping for literal text that will be embedded in a pattern.

Reach for RegExp when you need to build a regular expression from user or data-driven text, check whether an unknown value is already a RegExp, or access the native constructor without leaving the Effect namespace.

3 exports Added in v2.0.0 Source

Constructors

RegExp

Added in v4.0.0 Source

Exposes the JavaScript regular expression constructor from globalThis.

When to use

Use to construct JavaScript regular expressions through the Effect module namespace.

Signature

declare const RegExp: RegExpConstructor

Example

(Creating a regular expression)

import { RegExp } from "effect"

const pattern = new RegExp.RegExp("hello", "i")
pattern // => /hello/i
pattern.test("Hello World") // => true
pattern.test("goodbye") // => false

Guards

isRegExp

Added in v3.9.0 Source

Checks whether a value is a RegExp.

When to use

Use to validate unknown input before treating it as a regular expression.

Signature

declare const isRegExp: (input: unknown) => input is RegExp

Example

(Checking for regular expressions)

import { RegExp } from "effect"

RegExp.isRegExp(/a/) // => true
RegExp.isRegExp("a") // => false

Transforming

escape

Added in v2.0.0 Source

Escapes special characters in a regular expression pattern.

When to use

Use to turn literal text into a safe regular expression pattern fragment.

Signature

declare function escape(string: string): string

Example

(Escaping a pattern string)

import { RegExp } from "effect"

RegExp.escape("a*b") // => "a\\*b"