Pure Conditions Utility Functions

1.2.3 · active · verified Sun Apr 19

pure-conditions is a JavaScript utility library providing a collection of pure, isolated functions designed to simplify common conditional logic. It offers methods for tasks like checking for duplicates in arrays, determining if an object or array is empty, validating email formats, and string manipulations such as checking if a string ends with a specific substring. The current stable version is 1.2.3. As a small, focused utility, it doesn't adhere to a strict release cadence but updates as new common conditions are identified or minor improvements are made. Its key differentiators include its adherence to pure function principles (no side effects, predictable output) and the complete isolation of functions, which benefits bundlers and compilers by allowing for efficient tree-shaking and minimal bundle sizes. It focuses on functional programming paradigms for robustness and testability.

Common errors

```
TypeError: Cannot read properties of undefined (reading 'hasDuplicates')
```
cause Attempting to call `hasDuplicates` on an `undefined` or incorrectly imported object, often due to a wrong import statement (e.g., default import or no destructuring).

fix Ensure you are using named imports with destructuring: `import { hasDuplicates } from 'pure-conditions';` or `const { hasDuplicates } = require('pure-conditions');`
```
SyntaxError: Unexpected token '{'
```
cause Using `import { someFunction } from 'pure-conditions';` in a CommonJS module context (a file without `'type': 'module'` in `package.json` and `.js` extension, or a `.cjs` file).

fix Either convert your file/project to an ESM module by setting `'type': 'module'` in `package.json` or rename the file to `.mjs`, or use CommonJS `require`: `const { someFunction } = require('pure-conditions');`

Warnings

gotcha The library primarily uses named exports. Attempting to use a default import (e.g., `import PConditions from 'pure-conditions'`) will result in `undefined` or an error, as there is no default export.
Fix: Always use named imports with destructuring: `import { functionName } from 'pure-conditions';`
gotcha As a 'pure' utility, functions are designed for immutable operations. While convenient, ensure you understand that these functions do not modify their inputs, but rather return a boolean or new value based on the condition.
Fix: No fix needed, this is by design. Understand that functions like `hasDuplicates` do not change the array, they only evaluate it.
gotcha Older Node.js environments or build setups might require specific configuration for ESM `import` statements. The README's examples use CommonJS `require`, which is universally supported but less modern.
Fix: For modern Node.js and bundlers, use ESM `import`. If targeting older environments, ensure your build setup transpiles ESM to CommonJS, or stick to `require()` if feasible for your module type.

Install

npm install pure-conditions npm
yarn add pure-conditions yarn
pnpm add pure-conditions pnpm

Imports

hasDuplicates
wrong:
```
const { hasDuplicates } = require('pure-conditions');
```
correct:
```
import { hasDuplicates } from 'pure-conditions';
```
CommonJS `require` is shown in the README, but ESM `import` is preferred for modern Node.js and browser environments.

isEmpty

wrong:

import isEmpty from 'pure-conditions'; // Incorrect default import

correct:

import { isEmpty } from 'pure-conditions';

All functions are named exports; there is no default export. Destructuring is required.

isEmail
wrong:
```
require('pure-conditions').isEmail;
```
correct:
```
import { isEmail } from 'pure-conditions';
```
While functional, direct property access like `require('pkg').func` can sometimes lead to issues with bundlers or static analysis compared to explicit destructuring.

Quickstart

Demonstrates importing and using several utility functions like `hasDuplicates`, `isEmpty`, `endsWith`, and `isEmail` to perform common conditional checks.

import { hasDuplicates, isEmpty, endsWith, isEmail } from 'pure-conditions';

console.log('--- pure-conditions Quickstart ---');

// Check for duplicates in an array
const listWithDuplicates = ['apple', 'banana', 'apple'];
console.log(`Has duplicates (['apple', 'banana', 'apple']): ${hasDuplicates(listWithDuplicates)}`);

// Check if an object is empty
const emptyObject = {};
const filledObject = { id: 1 };
console.log(`Is {} empty? ${isEmpty(emptyObject)}`);
console.log(`Is { id: 1 } empty? ${isEmpty(filledObject)}`);

// Check if a string ends with another string
const sentence = 'Hello, world!';
console.log(`'Hello, world!' ends with 'world!'? ${endsWith(sentence, 'world!')}`);
console.log(`'Hello, world!' ends with 'universe'? ${endsWith(sentence, 'universe')}`);

// Validate an email address
const validEmail = 'test@example.com';
const invalidEmail = 'invalid-email';
console.log(`'test@example.com' is a valid email? ${isEmail(validEmail)}`);
console.log(`'invalid-email' is a valid email? ${isEmail(invalidEmail)}`);

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