Integrates JavaScript engines across platforms, enabling JavaScript evaluation and bridging through a multiplatform API. Offers V8 engine support for JVM/Android and native support for iOS/macOS.
A Kotlin Multiplatform library that provides JavaScript engine integration for multiple platforms (Android, iOS, macOS, JVM).
JsWebViewContext executes scripts through the native WebView API, including on pages with script-src 'none' or without unsafe-eval. It preserves access to the page's globals and DOM, object identity, functions, promises and JavaScript exceptions. The page's CSP still applies to explicit eval() calls made by page or plugin code.
The bridge parses scripts with a bundled Acorn parser and captures their completion values before native execution. See the evaluation implementation notes for the protocol and parser update procedure.
The WebView runtime uses a non-enumerable symbol property instead of a string-named
window property. Copying or deleting string properties such as __appZenmoneyJsBridge
does not affect its session. The runtime captures the native message channel during
initialization, so hiding its global or replacing postMessage afterwards does not
interrupt existing callbacks.
JsEventLoop.attachTo accepts a JsEventLoopPolicies object with three fields:
timers (, and their clear functions),
( and ), and ().
Each field is a with two required fields:
The action enums are nested in JsEventLoopPolicy: ExistingApiAction and
MissingApiAction. A group is present only when all its members are functions.
Missing or non-function members select ifMissing for the whole group;
INSTALL also replaces any remaining members to keep scheduling and cancellation
consistent. Installing nextTick creates when it is null or absent;
an existing object retains its other properties.
KEEP + SKIP leaves properties untouched without reading getters.
REPLACE + INSTALL installs functions without reading the originals. Other
combinations check availability and may invoke getters. Getter errors and failures
to observe or install functions fail attachment and roll back its changes; they
are not treated as missing APIs. Both replacement and installation support
configurable read-only placeholders.
Each field defaults to REPLACE + INSTALL, so attachTo(context) installs all
three groups. For a page context that should only observe browser timers:
import app.zenmoney.jsbridge.JsEventLoopPolicy.ExistingApiAction.KEEP
import app.zenmoney.jsbridge.JsEventLoopPolicy.ExistingApiAction.OBSERVE
import app.zenmoney.jsbridge.JsEventLoopPolicy.MissingApiAction.SKIP
val untouched = JsEventLoopPolicy(ifPresent = KEEP, ifMissing = SKIP)
eventLoop.attachTo(
context,
policies = JsEventLoopPolicies(
timers = JsEventLoopPolicy(
ifPresent = OBSERVE,
ifMissing = SKIP,
),
immediate = untouched,
nextTick = untouched,
),
)
This leaves , and untouched, including when absent. Omitted fields keep their own defaults. To observe all available groups, pass an policy to all three fields. Use to also provide missing APIs, or to require existing implementations. provides only missing groups; work through existing groups is not awaited. A object can be reused across contexts or adjusted with , , or .
Observation retains the original scheduler's timing, handles, execution and error
handling. Cancellation restores the original descriptors where the page has not
replaced or locked the wrappers; scheduled work continues.
Reattaching the same context keeps its original configuration. Observation covers
only calls through the installed wrappers: earlier registrations, saved original
functions and string timer handlers are excluded, and returned callback promises
are not awaited. Observed intervals keep run() pending until cleared through a
wrapped clear function. Queued event-loop callbacks continue to run while the loop
awaits native Promises.
This is resilience within the page's JavaScript realm, not isolation from arbitrary page changes. Removing the bridge's symbol property, modifying JavaScript built-ins, or hiding the native channel before initialization can still prevent execution. A detached context must be replaced; native WebView navigation and cookie APIs have an independent lifetime.
Primitive JavaScript BigInt values are exposed as JsNumber with Double precision and are passed back to JavaScript as number. Boxed BigInt values (Object(1n)) remain JsObject instances and retain their JavaScript object identity.
On JVM, Javet 5.0.11 can truncate some BigInt values outside the signed 64-bit range before the bridge receives them; for example, 9223372036854775808n can acquire the wrong sign. Convert such values explicitly with Number(value) in JavaScript to avoid this limitation. The bridge does not add JavaScript wrappers to ordinary operations to work around it.
JsContext().use { context ->
val sum = jsScoped(context) {
context.globalThis["sumOf"] = JsFunction { args ->
JsNumber(args.sumOf { it.double })
}
eval("sumOf(1, 2, 3, 4, 5)").double
}
println("sum = $sum") // sum = 15.0
}
setTimeoutsetIntervalimmediatesetImmediateclearImmediatenextTickprocess.nextTickJsEventLoopPolicy| Field | Action | Behavior |
|---|
ifPresent | KEEP | Leave the existing functions unchanged, without awaiting their work. |
ifPresent | OBSERVE | Wrap existing functions and await callbacks through their original scheduler. |
ifPresent | REPLACE | Replace the group with functions scheduled by this event loop. |
ifMissing | SKIP | Leave the entire group untouched. |
ifMissing | INSTALL | Install the entire group with functions scheduled by this event loop. |
ifMissing | FAIL | Fail attachment with a JsException identifying the missing group and function. |
processprocesssetImmediateclearImmediateREPLACE + INSTALLOBSERVE + SKIPOBSERVE + INSTALLOBSERVE + FAILKEEP + INSTALLJsEventLoopPoliciescopy(timers = ...)copy(immediate = ...)copy(nextTick = ...)Surfaced from shared tags and platforms — no rankings paid for.