README.md

@beautify-lang/javascript

A lightweight TypeScript utility library that makes JavaScript/TypeScript code easier to read and validate. Provides clean, type-safe helpers for condition checking, string validation, and array transformations.

Features

• Condition Class – Create expressive, reusable validation conditions with clear pass/fail semantics and optional timestamps
• String Validators – Chainable string checks (JSON validation, empty, length, numeric, case-sensitive, regex matching)
• Array Utilities – Convert arrays to JSON strings, Sets, or unique arrays
• Type Safety – Fully typed with TypeScript for IDE autocomplete and error prevention
• Zero Dependencies – Pure TypeScript, no external dependencies required

Installation

npm install @beautify-lang/js
# or
pnpm add @beautify-lang/js
# or
yarn add @beautify-lang/js

Usage

Condition Validation

Create reusable conditions that validate expected outputs with clear logging:

import { Condition } from '@beautify-lang/js';

const isEven = new Condition(
  () => 42 % 2,
  0,
  'Number is even'
);

if (isEven.passes()) {
  console.log('Condition passed!');
} else {
  // Logs: [@beautify-lang/js at 2026-09-27 12:00:00]: Condition "Number is even" failed. Given Callback returned 0, expected output was 0
}

// Check if condition fails
if (isEven.fails()) {
  console.log('Condition failed!');
}

Disable timestamps in logs:

const condition = new Condition(
  () => myValue,
  expectedValue,
  'My validation',
  console.warn,
  false  // logTimestamp: false disables timestamp in log messages
);

String Validation

Chainable string validators for common checks:

import { isString } from '@beautify-lang/js';

const input = '{ "valid": true }';

// Check if valid JSON
if (isString(input).validJSON()) {
  console.log('Valid JSON string');
}

// Check string properties
isString(input).empty();        // false
isString(input).ofLength(17);   // true
isString(input).numeric();       // false
isString(input).uppercase();     // false
isString(input).lowercase();     // false
isString(input).matches(/\d+/); // false

Array Conversion

Transform arrays with clean, declarative syntax:

import { convertArray } from '@beautify-lang/js';

const numbers = [1, 2, 2, 3, 3, 3];

// Convert to JSON string
const json = convertArray(numbers).toJsonString();
// "[1,2,2,3,3,3]"

// Convert to Set
const set = convertArray(numbers).toSet();
// Set {1, 2, 3}

// Get unique values as array
const unique = convertArray(numbers).toUniqueArray();
// [1, 2, 3]

Utility Functions

import { not } from '@beautify-lang/js';

const result = not(true); // false
const truthy = not(false); // true

API Reference

Condition<ExpectedOutputType>

A class for creating reusable validation conditions.

Constructor

new Condition<T>(
  cb: () => unknown,
  expectedOutput: T,
  label: string,
  logger: (...args: any[]) => void = console.warn,
  logTimestamp: boolean = true
)

Parameters:

• cb – Callback function that returns the value to validate
• expectedOutput – Expected output to compare against
• label – Human-readable label for the condition (used in log messages)
• logger – Optional logging function (defaults to console.warn)
• logTimestamp – When true (default), includes ISO timestamp in log messages

Methods

• passes(): boolean – Returns true if callback output matches expected output. Logs failure details with timestamp if mismatch.
• fails(): boolean – Returns true if callback output does NOT match expected output.

isString(str: string)

Returns an object with chainable string validation methods:

• validJSON(): boolean – Checks if the string is valid JSON
• empty(): boolean – Checks if the string is empty
• ofLength(expectedLength: number): boolean – Checks if the string has the expected length
• numeric(): boolean – Checks if the string contains only numeric characters
• uppercase(): boolean – Checks if the string is uppercase (non-empty)
• lowercase(): boolean – Checks if the string is lowercase (non-empty)
• matches(regex: RegExp): boolean – Checks if the string matches the given regex

convertArray<ItemType>(array: ItemType[])

Returns an object with array transformation methods:

• toJsonString(): string – Converts the array to a JSON string
• toSet(): Set<ItemType> – Converts the array to a Set
• toUniqueArray(): ItemType[] – Returns a new array with unique values

not<T>(value: T): boolean

Returns the boolean negation of the input value.

License

This project is licensed under the Apache License 2.0 - see the LICENSE file for details.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

Author

Vedansh Shetti (@vedanshshetti)