https://github.com/donmccurdy/expression-eval

JavaScript expression parsing and evaluation.
https://github.com/donmccurdy/expression-eval

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JavaScript expression parsing and evaluation.

• Host: GitHub
• URL: https://github.com/donmccurdy/expression-eval
• Owner: donmccurdy
• License: mit
• Archived: true
• Created: 2017-04-12T05:58:04.000Z (over 7 years ago)
• Default Branch: main
• Last Pushed: 2023-06-19T21:01:18.000Z (over 1 year ago)
• Last Synced: 2024-09-07T14:37:52.196Z (2 months ago)
• Language: TypeScript
• Homepage:
• Size: 847 KB
• Stars: 196
• Watchers: 8
• Forks: 47
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • Funding: .github/FUNDING.yml
  • License: LICENSE

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# expression-eval

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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 ⚠️ **UNMAINTAINED:** The `expression-eval` npm package is no longer maintained.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](#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](https://www.npmjs.com/package/vm2).

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## Installation

Install:

```

npm install --save expression-eval

```

Import:

```js

// ES6

import { parse, eval } from 'expression-eval';

// CommonJS

const { parse, eval } = require('expression-eval');

// UMD / standalone script

const { parse, eval } = window.expressionEval;

```

## API

### Parsing

```javascript

import { parse } from 'expression-eval';

const ast = parse('1 + foo');

```

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

```json

{

  "type": "BinaryExpression",

  "operator": "+",

  "left": {

    "type": "Literal",

    "value": 1,

    "raw": "1"

  },

  "right": {

    "type": "Identifier",

    "name": "foo"

  }

}

```

### Evaluation

```javascript

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

```javascript

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()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/eval#Do_not_ever_use_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](https://www.npmjs.com/package/vm2).

## License

MIT License.