jint

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# Jint

Jint is a modern ECMAScript interpreter for .NET. It runs JavaScript directly in
your process without native dependencies, bytecode generation, or a separate
runtime.

Jint targets .NET Framework 4.7.2, .NET Standard 2.0/2.1, .NET 8, and .NET 10.
Start with the [documentation](https://sebastienros.github.io/jint/) or install
the core package:

```bash
dotnet add package Jint
```

## Quick start

The examples below assume `using Jint;`.

### Evaluate JavaScript

<!-- snippet: readme-evaluate -->
```csharp
var engine = new Engine();
var result = engine.Evaluate("40 + 2").AsNumber();
```
<!-- endSnippet -->

### Expose .NET and call JavaScript

<!-- snippet: readme-expose-and-invoke -->
```csharp
var engine = new Engine()
    .SetValue("log", new Action<string>(Console.WriteLine))
    .Execute("""
        function greet(name) {
            const message = `Hello, ${name}!`;
            log(message);
            return message;
        }
        """);

var greeting = engine.Invoke("greet", "Ada").AsString();
```
<!-- endSnippet -->

### Prepare code that runs repeatedly

<!-- snippet: readme-prepare -->
```csharp
var script = Engine.PrepareScript(
    "items.reduce((sum, value) => sum + value, 0)",
    source: "sum.js",
    strict: true);

var engine = new Engine();
engine.SetValue("items", new[] { 1, 2, 3 });

var total = engine.Evaluate(in script).AsNumber();
```
<!-- endSnippet -->

`Prepared<Script>` and `Prepared<Module>` are thread-safe and may be shared
across engines. JavaScript objects are not: a `JsValue` that contains an object
belongs to the engine and realm that created it.

## Features

- Modern ECMAScript, modules, promises, async functions, generators, `Intl`,
  and `Temporal`
- Direct projection of .NET values, delegates, objects, collections, and types
- Synchronous and asynchronous module loaders
- Execution constraints, hardened untrusted-code defaults, and security
  diagnostics
- Profiling, statement coverage, debugging, and Chrome DevTools Protocol
  integration
- Opt-in Web APIs and Node-compatible modules
- A headless browser, command-line tool, and MCP server

Browser and Node APIs are not installed by default. Hosts explicitly grant the
capabilities each script needs.

## Used by

Projects using Jint include
[RavenDB](https://github.com/ravendb/ravendb),
[EventStoreDB](https://github.com/EventStore/EventStore),
[Orchard Core](https://github.com/OrchardCMS/OrchardCore),
[Elsa Workflows](https://github.com/elsa-workflows/elsa-core),
[Docfx](https://github.com/dotnet/docfx), and
[JavaScript Engine Switcher](https://github.com/Taritsy