ilib-ctype

ilib-ctype

Utility functions for dealing with character types.

Installation

npm install ilib-ctype

or

yarn add ilib-ctype

CType Functions

The CType functions are modeled after the posix ctype functions for C/C++. The data for all of the CType functions are derived from the Unicode Character Database so that they can be called with any character in Unicode. (Many posix implementations do not support Unicode!)

Because Javascript does not have an intrinsic character type, the arguments for these functions are strings. Only the very first character in the string is examined to determine the output of the function. The rest of the string is ignored.

The functions are as follows:

• isAlnum - is the character alpha numeric?
• isAlpha - is the character alphabetic?
• isAscii - is the character part of the ASCII subset?
• isBlank - is the character blank?
• isCntrl - is the character a control character?
• isDigit - is the character a digit?
• isGraph - is the character a graphic character?
• isIdeo - is the character an ideographic (Asian) character?
• isLower - is the character lower-case? For scripts that do not have the concept of cases, this always returns true.
• isPrint - is the character printable on the screen?
• isPunct - is the character a punctuation character?
• isScript - does the given character belong to the named script?
• isSpace - is the character a whitespace character?
• isUpper - is the character upper-case? For scripts that do not have the concept of case, this always returns true.
• isXdigit - is this character a hexadecimal digit?

Additionally, there is a withinRange() function which returns true if the given character is within the named Unicode range.

import { withinRange } from "ilib-ctype";

console.log(withinRange("\uFE2A", "HalfMarks")); // prints true

There is also a hasUCDCharProperty() function which returns true if a character has a given Unicode general-category property. You may pass either the short code ("Mn") or the long Unicode name ("Nonspacing_Mark"):

import { hasUCDCharProperty } from "ilib-ctype";

console.log(hasUCDCharProperty("\u0308", "Nonspacing_Mark")); // true
console.log(hasUCDCharProperty(0x093E, "Mc")); // true (Spacing_Mark)

Using the CType Functions

All of the functions are exported from the package in general. Here is an example of how you would use the isAlpha function.

import { isAlpha } from "ilib-ctype";

console.log(isAlpha("a")); // prints true
console.log(isAlpha("3")); // prints false

If you are using this package in a webpack bundle, make sure to only import the ctype functions you need in order to minimize the final size of your bundle. That is, do not import * as that will bring in a bunch of data that you probably don't need. Tree shaking in the latest webpack will ensure that only the data needed for the functions you are using will be included in your bundle.

License

Copyright 2021-2026, JEDLSoft

This package is released under the Apache License, Version 2.0. The full license text is available in the LICENSE file in the ilib-mono repository on GitHub.

Release Notes

See CHANGELOG.md.