https://github.com/thomashambach/ncalcjs
NCalc is a mathematical expressions evaluator in JavaScript/TypeScript. NCalc can parse any expression and evaluate the result, including static or dynamic parameters and custom functions.
https://github.com/thomashambach/ncalcjs
antlr4 expression javascript ncalc typescript
Last synced: about 2 months ago
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NCalc is a mathematical expressions evaluator in JavaScript/TypeScript. NCalc can parse any expression and evaluate the result, including static or dynamic parameters and custom functions.
- Host: GitHub
- URL: https://github.com/thomashambach/ncalcjs
- Owner: ThomasHambach
- Created: 2023-01-14T03:12:54.000Z (over 2 years ago)
- Default Branch: main
- Last Pushed: 2023-08-19T03:53:40.000Z (almost 2 years ago)
- Last Synced: 2024-05-01T12:55:32.113Z (about 1 year ago)
- Topics: antlr4, expression, javascript, ncalc, typescript
- Language: TypeScript
- Homepage:
- Size: 275 KB
- Stars: 7
- Watchers: 2
- Forks: 1
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- Funding: .github/FUNDING.yml
Awesome Lists containing this project
README
# NCalcJS
[](https://www.npmjs.com/package/ncalcjs)
[](https://sonarcloud.io/summary/new_code?id=ThomasHambach_NcalcJS)
[](LICENSE)
[](https://github.com/thomashambach/NCalcJS/graphs/contributors)
NCalc is a mathematical expressions evaluator in JavaScript/TypeScript. NCalc can parse any
expression and evaluate the result, including static or dynamic parameters and custom functions. You
may also want to look at the example running on CloudFlare workers
https://github.com/ThomasHambach/expression.worker
## Project Description
### Browser Support
In theory, all browsers supporting ECMAScript 5.1.
In practice, this target has been extensively tested against:
* Firefox 34.0.5
* Safari 8.0.2
* Chrome 39.0.2171
* Explorer 11.0.3
### Is NodeJS supported?
The package has been extensively tested against Node.js 14 LTS.
### Installation
Get the package from npm.org (https://www.npmjs.com/package/ncalcjs) by running
npm i --s ncalcjs
or with yarn
yarn ncalcjs
### Usage
For documentation here is the table of content:
- [description](docs/description.md): overall concepts, usage and extensibility points
- [operators](docs/operators.md): available standard operators and structures
- [functions](docs/functions.md): list of already implemented functions
- [parameters](docs/parameters.md): on how to use parameters expressions
#### Basic
```typescript
import {Expression} from 'ncalcjs';
const e = new Expression('2 + 3 * 5');
console.log(e.Evaluate()); // 17
```
#### Custom Functions
The API compared to C# NCalc is a little different. In NCalcJS you define custom functions in the
following way. Each function is expected to be of the type `EvaluateFunctionHandler`.
```typescript
const e = new Expression('SecretOperation(3, 6)');
e.EvaluateFunction['SecretOperation'] = (args: FunctionArgs) => {
args.Result = args.Parameters[0].Evaluate() + args.Parameters[1].Evaluate();
};
console.log(e.Evaluate()); // 9
```
#### Handling Errors
You can use the method `Expression.HasErrors()` to check for any errors that are present in your
expression. The errors details are stored in `Expression.errors`.
```typescript
import {Expression} from 'ncalcjs';
const e = new Expression('2 + 3 * 5');
if (e.HasErrors()) {
console.error(e.errors);
}
```
### Known Issues
- `Round` does not return the correct value
## Building
Install all dependencies
npm install
Before we can run our build, we need to install `ts-patch` that will change our `paths` configured
in `tsconfig.json`. Note that you have to run this every time after running `npm install`.
npm run prepare
Build the distribution version
npm run build
### ANTLR & Grammar
Note that the files, except for `NCalc.g4` in `/src/Grammar` are automatically generated. Any
changes you wish to make there are to be made in `NCalc.g4`. You will need Java runtime installed on
your system to generate these files.
To update the generated files, run this commond inside `/src/Grammar`.
antlr4 -Dlanguage=TypeScript NCalc.g4
## Contributors
Special thanks to:
* [Thaina](https://github.com/Thaina) for creating the basis of this package's ANTLR4 grammar
file. Original C# version available at: https://github.com/Thaina/NCalc2/blob/master/grammer/NCalc.g
* [robmarti12](https://github.com/robmarti12) for implementing the static `Compile` as in original NCalc.
## Related projects
### [NCalc](https://github.com/ncalc/ncalc/)
NCalc C# implementation.
### [NCalc-Async](https://github.com/ncalc/ncalc-async/)
Pure asynchronous C# implementation of NCalc by [Peter Liljenberg](https://github.com/petli).
### [PanoramicData.NCalcExtensions](https://github.com/panoramicdata/PanoramicData.NCalcExtensions)
Extension functions for NCalc in C# to handle many general functions,
including string functions, switch, if, in, typeOf, cast etc.
Developed by David, Dan and all at [Panoramic Data](https://github.com/panoramicdata).
### [Expression.worker](https://github.com/ThomasHambach/expression.worker)
Starter kit to run NCalcJS in a cloudflare worker.