https://github.com/umutozel/jokenizer

:dragon: JavaScript expression tokenizer and evaluator
https://github.com/umutozel/jokenizer

evaluator expression javascript parser tokenizer typescript

Last synced: 10 months ago
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:dragon: JavaScript expression tokenizer and evaluator

• Host: GitHub
• URL: https://github.com/umutozel/jokenizer
• Owner: umutozel
• License: mit
• Created: 2018-08-12T11:31:17.000Z (over 7 years ago)
• Default Branch: main
• Last Pushed: 2025-02-15T19:44:33.000Z (12 months ago)
• Last Synced: 2025-04-28T11:16:13.600Z (10 months ago)
• Topics: evaluator, expression, javascript, parser, tokenizer, typescript
• Language: TypeScript
• Homepage:
• Size: 670 KB
• Stars: 17
• Watchers: 4
• Forks: 2
• Open Issues: 0
• Metadata Files:
  • Readme: readme.md
  • Contributing: .github/CONTRIBUTING.md
  • License: LICENSE

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README

          
# Jokenizer - JavaScript Expression Parser and Evaluator

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jokenizer is just a simple library to parse JavaScript expressions and evaluate them with custom scopes.

Written completely in TypeScript.

## Installation

```shell

npm i jokenizer

```

## Let's try it out

```JavaScript

import { tokenize, evaluate } from 'jokenizer';

const expression = tokenize('{ a: v1, b }');

const scope = { v1: 3, b: 5 };

const value = evaluate(expression, scope);

/*

expression =

{

    "type": "O",          // ObjectExpression

    "members": [{

        "type": "A",      // AssignExpression

        "name": "a",

        "right": {

            "type": "V",  // VariableExpression

            "name": "v1"

        }

    }, {

        "type": "V",

        "name": "b"

    }]

}

value = { "a": 3, "b": 5 }     // evaluated value

*/

```

## Supported Expression Types

### LiteralExpression

```JavaScript

evaluate(tokenize('42'));               //  42

evaluate(tokenize('42.4242'));          //  42.4242

evaluate(tokenize('"4\'2"'));           //  "4'2"

evaluate(tokenize('true'));             //  true

evaluate(tokenize('false'));            //  false

evaluate(tokenize('null'));             //  null

```

### VariableExpression

```JavaScript

evaluate(tokenize('Name'), { Name: 'Alan' });       //  'Alan'

```

### UnaryExpression

```JavaScript

evaluate(tokenize('-Str'), { Str: '5' });               //  -5

evaluate(tokenize('+Str'), { Str: '5' });               //  5

evaluate(tokenize('!IsActive'), { IsActive: false });   //  true

evaluate(tokenize('~index'), { index: -1 });            //  0

```

### GroupExpression

```JavaScript

evaluate(tokenize('(a, b)'), { a: 4, b: 2 });   //  [1, 2]

evaluate(tokenize('a, b'), { a: 4, b: 2 });     //  [4, 2]

evaluate(tokenize('(a)'), { a: 4 });            //  4   - if expression count is 1, returns its value

```

### ObjectExpression

```JavaScript

evaluate(tokenize('{ a: v1, b }'), { v1: 3, b: 5 });    //  { a: 3, b: 5 }

```

### ArrayExpression

```JavaScript

evaluate(tokenize('[ a, 1 ]'), { a: 0 });               //  [0, 1]

```

### BinaryExpression

```JavaScript

evaluate(tokenize('v1 <= v2'), { v1: 5, v2: 3 });           //  false

evaluate(tokenize('v1 % v2'), { v1: 5, v2: 3 });            //  2

evaluate(tokenize('v1 * v2'), { v1: 5, v2: 3 });            //  15

evaluate(tokenize('v1 && v2'), { v1: true, v2: false });    //  false

evaluate(tokenize('1 + 2 * 3'));                            //  7   - supports operator precedence

```

### MemberExpression

```JavaScript

evaluate(tokenize('Company.Name'), { Company: { Name: 'Netflix' } });       //  'Netflix'

```

### IndexerExpression

```JavaScript

evaluate(tokenize('Company["Name"]'), { Company: { Name: 'Netflix' } });                //  'Netflix'

evaluate(tokenize('Company[key]'), { Company: { Name: 'Netflix' }, key: 'Name' });      //  'Netflix'

```

### FuncExpression

```JavaScript

const f = evaluate(tokenize('(a, b) => a < b'));

f(2, 1);        //  false

const f = evaluate(tokenize('function(a, b) { return a < b; }'));

f(2, 1)         //  false

```

### CallExpression

```JavaScript

evaluate(tokenize('test(42, a)'), { test: (a, b) => a * b }, { a: 2 });     //  84

```

### TernaryExpression

```JavaScript

evaluate(tokenize('check ? 42 : 21'), { check: true });     //  42

```

## License

Jokenizer is under the [MIT License](LICENSE).