Package Exports

expression-eval
expression-eval/dist/expression-eval.js
expression-eval/dist/expression-eval.module.js

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (expression-eval) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

expression-eval

JavaScript expression parsing and evaluation.

⚠️ UNMAINTAINED: The expression-eval npm package is no longer maintained. The package was originally published as part of a now-completed personal project, and I do not have incentives to continue maintenance. Please feel free to use the code, but be aware that support and updates will not be available.

⚠️ SECURITY NOTICE: As mentioned under Security below, this library does not attempt to provide a secure sandbox for evaluation. Evaluation involving user inputs (expressions or values) may lead to unsafe behavior. If your project requires a secure sandbox, consider alternatives such as vm2.

Installation

Install:

npm install --save expression-eval

Import:

// ES6
import { parse, eval } from 'expression-eval';
// CommonJS
const { parse, eval } = require('expression-eval');
// UMD / standalone script
const { parse, eval } = window.expressionEval;

API

Parsing

import { parse } from 'expression-eval';
const ast = parse('1 + foo');

The result of the parse is an AST (abstract syntax tree), like:

{
  "type": "BinaryExpression",
  "operator": "+",
  "left": {
    "type": "Literal",
    "value": 1,
    "raw": "1"
  },
  "right": {
    "type": "Identifier",
    "name": "foo"
  }
}

Evaluation

import { parse, eval } from 'expression-eval';
const ast = parse('a + b / c'); // abstract syntax tree (AST)
const value = eval(ast, {a: 2, b: 2, c: 5}); // 2.4

Alternatively, use evalAsync for asynchronous evaluation.

Compilation

import { compile } from 'expression-eval';
const fn = compile('foo.bar + 10');
fn({foo: {bar: 'baz'}}); // 'baz10'

Alternatively, use compileAsync for asynchronous compilation.

Security

Although this package does avoid the use of eval(), it cannot guarantee that user-provided expressions, or user-provided inputs to evaluation, will not modify the state or behavior of your application. This library does not attempt to provide a secure sandbox for evaluation. Evaluation of arbitrary user inputs (expressions or values) may lead to unsafe behavior. If your project requires a secure sandbox, consider alternatives such as vm2.

License

MIT License.