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
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
The package has been extensively tested against Node.js 14 LTS.
Get the package from npm.org (https://www.npmjs.com/package/ncalcjs) by running
npm i --s ncalcjs
or with yarn
yarn ncalcjs
For documentation here is the table of content:
- description: overall concepts, usage and extensibility points
- operators: available standard operators and structures
- functions: list of already implemented functions
- parameters: on how to use parameters expressions
import {Expression} from 'ncalcjs';
const e = new Expression('2 + 3 * 5');
console.log(e.Evaluate()); // 17The 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.
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()); // 9You 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.
import {Expression} from 'ncalcjs';
const e = new Expression('2 + 3 * 5');
if (e.HasErrors()) {
console.error(e.errors);
}Rounddoes not return the correct value
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
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
Special thanks to:
- 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 for implementing the static
Compileas in original NCalc.
NCalc C# implementation.
Pure asynchronous C# implementation of NCalc by Peter Liljenberg.
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.
Starter kit to run NCalcJS in a cloudflare worker.
