cel-js

cel-js is a powerful and efficient parser and evaluator for Google's Common Expression Language (CEL), built on the robust foundation of the Chevrotain parsing library. This library aims to provide a seamless and easy-to-use interface for working with CEL in JavaScript environments.

Live Demo 🚀

Try out cel-js in your browser with the live demo.

Features ✨

• 🚀 Fast and Efficient Parsing: Leverages Chevrotain for high-performance parsing and evaluation
• 🌍 Isomorphic: Ready for server and browser
• 📦 ESM support
• 📚 Supported CEL Features:
  • Literals
    • int
    • uint
    • double
    • bool
    • string
    • bytes
    • list
    • map
    • null
  • Conditional Operators
    • Ternary (condition ? true : false)
    • Logical And (&&)
    • Logical Or (||)
  • Equality Operators (==, !=)
  • Relational Operators (<, <=, >, >=, in)
  • Arithmetic Operators (+, -, *, /, %)
  • Identifiers
    • Dot Notation (foo.bar)
    • Index Notation (foo["bar"])
  • Macros: (exists, has, size, etc.)
    • Exists (exists(foo))
    • Has (has(foo, "bar"))
    • Size (size(foo))
  • Unary Operators (!true, -123)

Installation

To install cel-js, use npm:

npm i cel-js

Usage

import { evaluate, parse } from 'cel-js'

// use `evaluate` to parse and evaluate an expression
evaluate('2 + 2 * 2') // => 6

evaluate('"foo" + "bar"') // => 'foobar'

evaluate('user.role == "admin"', { user: { role: 'admin' } }) // => true

// use `parse` to parse an expression, useful for validation purposes
const result = parse('2 + 2')

if (!result.isSuccess) {
  throw new Error('Invalid syntax')
}

// you can reuse the result of `parse` to evaluate the expression
evaluate(result.cst) // => 4

Known Issues

• Errors types and messages are not 100% consistent with the cel-go implementation