alecasg555/safe-expr-eval
GitHub: alecasg555/safe-expr-eval
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# safe-expr-eval
Fast and lightweight expression evaluator for JavaScript and TypeScript.
## Features
* Fast expression parsing and evaluation
* Lightweight and dependency-free
* Full TypeScript support
* Simple and familiar API
* Custom functions and constants
* ES2020+ compatible
* Well tested
## Installation
npm install safe-expr-eval
# Quick Start
## Basic Usage
import { Parser } from 'safe-expr-eval';
const parser = new Parser();
const expr = parser.parse('2 * x + 1');
console.log(expr.evaluate({ x: 3 })); // 7
console.log(expr.evaluate({ x: 10 })); // 21
## Direct Evaluation
import { evaluate } from 'safe-expr-eval';
const result = evaluate('10 + 5 * 2');
console.log(result); // 20
## Compiled Expressions
import { compile } from 'safe-expr-eval';
const fn = compile('price * quantity * (1 - discount)');
console.log(
fn({
price: 100,
quantity: 2,
discount: 0.1
})
); // 180
# Supported Operations
## Arithmetic
+ - * / %
## Comparison
== != > < >= <=
## Logical
and or not
&& || !
# Data Types
Numbers → 42, 3.14
Strings → "hello"
Booleans → true, false
Variables → price, user.name
# Custom Functions
const parser = new Parser();
parser.functions.max = Math.max;
parser.functions.min = Math.min;
parser.functions.round = Math.round;
const expr = parser.parse(
'round(max(a, b) * 1.5)'
);
console.log(
expr.evaluate({
a: 10,
b: 20
})
); // 30
# Constants
const parser = new Parser();
parser.consts.PI = Math.PI;
parser.consts.TAX_RATE = 0.15;
const expr = parser.parse(
'price * (1 + TAX_RATE)'
);
console.log(
expr.evaluate({
price: 100
})
); // 115
# API
## Parser
### Create parser
new Parser()
### Parse expression
parser.parse(expression)
### Evaluate expression
parser.evaluate(expression, variables?)
### Functions registry
parser.functions
### Constants registry
parser.consts
# Standalone Functions
## evaluate
evaluate(expression, variables?)
## compile
compile(expression)
# Testing
npm test
npm run test:coverage
# License
MIT
See the LICENSE file for details.
# Issues
Please open an issue if you find a bug or have a feature request.
# Author
Alejandro Castrillon
GitHub: https://github.com/
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