JSONLogic Rules Engine

A TypeScript wrapper around JSONLogic for evaluating business rules in Cloudflare Workers and other JavaScript environments.

Overview

This library provides a simple, type-safe interface for working with JSONLogic rules. It wraps the json-logic-js library and adds utilities for analyzing and validating rules before execution.

Features

• Evaluate Rules: Execute JSONLogic rules against provided data
• Analyze Dependencies: Extract all data keys required by a rule
• Validate Execution: Verify if a rule can be executed with given data
• Type Safety: Full TypeScript support with proper type definitions
• Cloudflare Workers Ready: Designed to run in edge environments
• Zero Dependencies: Minimal footprint with only JSONLogic as a dependency

Use Cases

• Business rule evaluation in serverless functions
• Dynamic permission systems
• Feature flags and A/B testing logic
• Data validation and filtering
• Conditional workflows

API Overview

import { evaluateRule, getRequiredKeys, canExecuteRule } from 'jsonlogic-rules';

// 1. Evaluate a rule with data
const rule = { "==": [{ "var": "user.age" }, 18] };
const data = { user: { age: 18 } };
const result = evaluateRule(rule, data); // true

// 2. Get required data keys from a rule
const keys = getRequiredKeys(rule); // ['user.age']

// 3. Check if rule can execute with provided data
const canRun = canExecuteRule(rule, data); // true

Installation

npm install

Development

See ARCHITECTURE.md for technical details and TASKS.md for implementation roadmap.

Target Runtime

This library is designed to work in Cloudflare Workers but is compatible with any JavaScript environment that supports ES modules.

Design Principles

• Simple: Minimal API surface with clear, focused functions
• Type-Safe: Leverage TypeScript for better developer experience
• Tested: Comprehensive unit tests for all functionality
• Standards: Follow JavaScript/TypeScript ecosystem best practices
• Maintainable: Clear code structure with good separation of concerns

JSONLogic Primer

JSONLogic rules are expressed as JSON objects with operators and values:

{
  "and": [
    { ">": [{ "var": "temp" }, 0] },
    { "<": [{ "var": "temp" }, 100] }
  ]
}

This rule checks if temperature is between 0 and 100. Learn more at jsonlogic.com.

License

MIT