is-char

is-char is a focused utility for one job: checking whether a value is a single-character string.

In many codebases, this check appears in validators, parsers, CLIs, text filters, and protocol handlers. Keeping it in a dedicated package makes that intent explicit and reusable across projects.

Why this package matters

• It standardizes a common validation rule used in input boundaries.
• It removes repeated ad-hoc checks from application code.
• It keeps behavior consistent across services and libraries.
• It is minimal, dependency-free, and safe to use in performance-sensitive paths.

Install

npm

npm i is-char

JSR

npx jsr add @arvid/is-char

Usage

import isChar from "is-char";

isChar("a"); // true
isChar("ab"); // false
isChar(""); // false
isChar(1); // false
isChar("a", { is: "a" }); // true
isChar("a", { is: "b" }); // false

API

isChar(value)

Returns true when:

• value is a string
• value.length === 1

Otherwise returns false.

isChar(value, { is })

If is is provided, isChar returns true only when:

• value is a single-character string
• is is a single-character string
• value === is

Character semantics

is-char follows JavaScript string semantics and checks value.length === 1 (UTF-16 code units). This means some multi-code-unit characters (for example many emoji) return false.

TypeScript

import isChar from "is-char";

Type definitions are included out of the box.