nounicode

A JavaScript/TypeScript utility to detect and enforce ASCII-only text. Choose between modern (0–255), extended (128–255), or standard (0–127) ASCII checks.

Installation

npm install nounicode

Usage

Import the default function or named helpers:

import isNoUnicode, {
  isModernASCII,
  isExtendedASCII,
  isStandardASCII,
  ASCIIType
} from 'nounicode';

API Reference

isNoUnicode(data: string, type: ASCIIType = 'MODERN'): boolean

Validate that every character in a string falls within one of three ASCII ranges.

Parameters

• data
  The input string to validate.

• type
  One of the following modes (defaults to MODERN):

  • MODERN Checks code points < 256
  • EXTENDED Checks code points > 127 and < 256
  • STANDARD Checks code points < 128

Returns

• true if all characters satisfy the chosen ASCII range.
• false as soon as a character falls outside the specified range.

Notes

• Uses String.prototype.codePointAt to handle all Unicode code points.
• Iterates through code units, so astral characters (code points > 0xFFFF) are split into two iterations.

Examples

isNoUnicode('Hello, World!');            // true (all < 256)
isNoUnicode('Résumé', 'STANDARD');       // false ('é' is 233)
isNoUnicode('Résumé', 'EXTENDED');       // true  (233 > 127 && 233 < 256)
isNoUnicode('😊', 'MODERN');             // false (128522 ≥ 256)

isModernASCII(cc: number): boolean

Check if a Unicode code point is within 0–255.

Parameters

• cc
  A Unicode code point (e.g., returned by str.codePointAt(idx)).

Returns

• true if 0 ≤ cc < 256
• false otherwise

Example

isModernASCII(200);  // true
isModernASCII(300);  // false

isExtendedASCII(cc: number): boolean

Check if a Unicode code point is within the extended ASCII range 128–255.

Parameters

• cc
  A Unicode code point to test.

Returns

• true if 128 < cc < 256
• false otherwise

Example

isExtendedASCII(129);  // true
isExtendedASCII(127);  // false

isStandardASCII(cc: number): boolean

Check if a Unicode code point is within the standard ASCII range 0–127.

Parameters

• cc
  A Unicode code point to test.

Returns

• true if 0 ≤ cc < 128
• false otherwise

Example

isStandardASCII(65);   // true ('A')
isStandardASCII(128);  // false

Types

export type ASCIIType = 'MODERN' | 'EXTENDED' | 'STANDARD';

• MODERN All byte values (0–255)
• EXTENDED Upper half of byte range (128–255)
• STANDARD Classic ASCII (0–127)

Performance

Validates a string in O(n) time, where n is the number of UTF-16 code units. Early exits on the first invalid character.

Examples

isNoUnicode('Hello World!');       // true
isNoUnicode('Café');               // false (contains 'é')
isNoUnicode('Café', 'EXTENDED');   // true