> ## Documentation Index
> Fetch the complete documentation index at: https://crafts69guy.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.
# API Reference
> Complete API documentation for Rule Engine JS
## Overview
Rule Engine JS provides a simple, powerful API for evaluating business rules. This section documents all public APIs.
## Core APIs
Core evaluation engine with caching and performance optimization
Event-driven engine with state tracking and history
Safe path resolution with security features
Fluent API for building rules programmatically
## Quick Start
```javascript theme={null}
import { createRuleEngine, createRuleHelpers } from 'rule-engine-js';
// Create engine
const engine = createRuleEngine();
// Build rules with helpers
const rules = createRuleHelpers();
const rule = rules.and(
rules.gte('age', 18),
rules.eq('role', 'admin')
);
// Evaluate
const result = engine.evaluateExpr(rule, { age: 25, role: 'admin' });
console.log(result.success); // true
```
## Import Paths
### ES Modules
```javascript theme={null}
import {
createRuleEngine,
StatefulRuleEngine,
createRuleHelpers
} from 'rule-engine-js';
```
### CommonJS
```javascript theme={null}
const {
createRuleEngine,
StatefulRuleEngine,
createRuleHelpers
} = require('rule-engine-js');
```
### TypeScript
```typescript theme={null}
import type { RuleEngine, RuleExpression } from 'rule-engine-js';
const engine: RuleEngine = createRuleEngine();
const rule: RuleExpression = { gte: ['age', 18] };
```
## API Categories
### Engine Management
* `createRuleEngine(config?)` - Create rule engine instance
* `engine.evaluateExpr(rule, context)` - Evaluate rule
* `engine.registerOperator(name, fn)` - Add custom operator
* `engine.getMetrics()` - Get performance metrics
### State Management
* `new StatefulRuleEngine(engine, options?)` - Create stateful engine
* `statefulEngine.evaluate(id, rule, context)` - Evaluate with state
* `statefulEngine.evaluateBatch(rules, context)` - Batch evaluation
* `statefulEngine.on(event, handler)` - Event listeners
### Rule Building
* `createRuleHelpers()` - Create helper factory
* `rules.eq(field, value)` - Equality check
* `rules.and(...conditions)` - Combine conditions
* `rules.validation.email(field)` - Built-in validators
### Utilities
* `pathResolver.resolve(context, path)` - Resolve path
* `pathResolver.resolveValueOrLiteral(context, value)` - Resolve or use literal
## Type Definitions
All APIs have TypeScript definitions:
```typescript theme={null}
// Engine configuration
interface EngineConfig {
strict?: boolean;
maxDepth?: number;
enableCache?: boolean;
maxCacheSize?: number;
}
// Evaluation result
interface EvaluationResult {
success: boolean;
value?: any;
error?: string;
}
// Rule expression
type RuleExpression = Record;
```
## Error Handling
All APIs throw or return structured errors:
```javascript theme={null}
try {
const result = engine.evaluateExpr(rule, context);
if (!result.success) {
console.error('Rule failed:', result.error);
}
} catch (error) {
console.error('Evaluation error:', error.message);
}
```
## Next Steps
Learn the core engine API
Build rules with fluent API
See all available operators
View practical examples