kudzu

Fast evaluation on ESTree-compatible ASTs

Features

• Comprehensive tests
• Fully asynchronous API and internals
• Esprima and Cherow compatible
• ECMA 3 and IE8 compatible
• ESNext support

Install

npm install esprima-eval

Usage

var esEval   = require('esprima-eval'),
    esprima  = require('esprima');
 
var ast   = esprima.parseScript(' ... '),
    scope = new esEval.Scope(globals);
 
scope.on('get', function () {
  // supports custom scope data handlers
});
 
scope.on('ConditionalExpression', function () {
  // supports custom lexical node handlers
});
 
scope.walk(ast, function (returnValue) {
  // done
});

Support

Runtime

• Strict mode
• Error handling
• Error skipping/resolution
• Protected global objects/prototypes

Globals

• Array
• Function
• Object
• Date
• Number
• RegExp
• String
• Proxy
• Symbol
• Math

Scope

• Scope chain
• Function scope (var)
• Block scope (let)

Operations

• Binary (&, |, ^)
• Mathematical (+, -, /, *, %)
• Increment before (++i, --i)
• Increment after (i++, i--)
• Add assignment
• Subtract assignment
• Multiply assignment
• Divide assignment
• typeof

Conditionals

• And/or
• Strict/non-strict equality
• <, >, <=, >=
• instanceof
• If statements

Loops

• For loops
• While loops
• break
• continue
• return

Functions

• Function declarations
• Anonymous closures
• Arrow functions
• Async functions
• Spread operator
• Object identity

Proxies

• Proxy constructor
• Has/get/set/delete property
• Get/set property descriptor
• Get/set prototype
• Apply

Promises

• Promise constructor
• Promise.then
• Promise.catch

Symbols

Errors

• Error constructor
• Stack traces
• Try/catch

# Prior Art

https://www.npmjs.com/package/esper.js https://www.npmjs.com/package/sandboxr https://github.com/NeilFraser/JS-Interpreter https://github.com/mozilla/narcissus/