Jint

Enabling Web APIs ​

Web APIs require .NET 8 or later and are absent from a default engine.

Enable the standard non-network, non-persistent set:

csharp
var engine = new Engine(options => options.UseWebApis());

Or select only the required features:

csharp
var engine = new Engine(options => options.UseWebApis(
    WebApiFeatures.Console |
    WebApiFeatures.Timers |
    WebApiFeatures.Encoding));

WebApiFeatures.Default includes console, timers, encoding, base64, structured clone, crypto, performance, events, URLs, files, navigator, streams, scheduling, messaging, reporting, compression, idle callbacks, and global error events. It deliberately excludes:

  • Fetch, EventSource, WebSocket, and XmlHttpRequest
  • Storage and CacheApi
  • FetchEvents, which lets script claim inbound requests
  • Workers, which asks the host to create engines and execution resources

Dedicated helpers such as UseFetch, UseStorage, UseCacheApi, and UseWorkers enable their flags and configure the associated options. Feature dependencies are expanded automatically; for example, fetch brings the events, URL, files, and streams surfaces it uses.

Globals are installed lazily and do not replace an own global already registered by the host. Only the principal realm is changed; a ShadowRealm receives none of these globals unless the host installs them.

Enabling an existing engine ​

For a pooled engine whose needs are known per request:

csharp
WebApiFeatures added = engine.WebApi.Enable(
    WebApiFeatures.Timers | WebApiFeatures.Events);

Enable is additive. Features cannot be removed, and requesting an installed feature is a no-op. The optional configuration callback receives a private copy of that engine's web options.

Enable features before capturing a reusable global snapshot. Restoring an older snapshot removes globals installed later but does not reset the feature record, so another Enable call cannot reinstall them.

Continue with Console and timers or review Fetch and networking before granting network access.