Usage Guides

These guides show you how to use JEXL Extended in your projects, from basic expression evaluation to advanced Monaco Editor integration.

Getting Started

Getting Started Guide

Learn the basics of JEXL Extended, installation, and your first expressions. Perfect for newcomers to JEXL.

Basic Usage

Comprehensive guide to using JEXL Extended as an expression evaluator in your JavaScript/TypeScript applications.

Integration Guides

Monaco Editor Integration

Complete guide to integrating JEXL with Monaco Editor for rich IDE experience with syntax highlighting, IntelliSense, and hover documentation.

Advanced Usage

Advanced patterns, performance optimization, error handling, and extending JEXL Extended with custom functionality.

Quick Examples

Expression Evaluation

import jexl from 'jexl-extended';

const data = { users: [{ name: "Alice", age: 28 }, { name: "Bob", age: 32 }] };
const result = jexl.evalSync('users|filter("value.age > 30")|map("value.name")', data);
// ["Bob"]

Monaco Editor Setup

import * as monaco from "monaco-editor";
import { Monaco } from "jexl-extended";

Monaco.registerJexlLanguage(monaco);
const editor = Monaco.createJexlEditor(monaco, container, {
  value: 'users|filter("value.active")|map("value.name")',
  theme: "vs-dark"
});

String Processing

const text = "  Hello World  ";
const result = jexl.evalSync('text | trim | lowercase | split(" ") | join("-")', { text });
// "hello-world"

Mathematical Operations

const numbers = [1, 2, 3, 4, 5];
const stats = jexl.evalSync('{
  sum: numbers | sum,
  average: numbers | average,
  max: numbers | max,
  count: numbers | length
}', { numbers });
// { sum: 15, average: 3, max: 5, count: 5 }

Common Use Cases

Data Transformation

Transform API responses, filter arrays, and manipulate objects with powerful expression chains.

Form Validation

Create dynamic validation rules using JEXL expressions that can be stored and evaluated at runtime.

Configuration Logic

Build flexible configuration systems where business rules are expressed as JEXL expressions.

Template Processing

Process templates with dynamic content using JEXL expressions for calculations and formatting.

Query Building

Create dynamic queries and filters using JEXL expressions that can be safely evaluated.

Choose Your Guide

• New to JEXL? Start with Getting Started
• Adding to existing project? Check Basic Usage
• Want rich editor experience? See Monaco Integration
• Need advanced features? Explore Advanced Usage

Each guide builds on the previous ones, so feel free to jump around based on your needs!