dart:js_interop#

Interoperability, "interop" for short, with JavaScript and browser APIs.

JavaScript interop allows a Dart program to interact with a JavaScript runtime. This can, for example, be to access JavaScript declarations and interact with JavaScript values, or to adapt Dart values so that they can be passed to and used by JavaScript code.

This JavaScript interop library works by introducing an abstraction over JavaScript values, a Dart type hierarchy ("JS types") which mirrors known JavaScript types, and a framework for introducing new Dart types that bind Dart type declarations to JavaScript values and external member declarations to JavaScript APIs.

This abstraction allows the same interop API to be used both when the Dart code is compiled to JavaScript and when compiled to Wasm.

See https://dart.dev/interop/js-interop for more details on usage, types, and previous JavaScript interop.

The types defined in this library only provide static guarantees. The runtime types differ based on the backend, so it is important to rely on static functionality like the conversion functions. Similarly, don't rely on is checks that involve JS types or JS-typed values. Furthermore, identical may also return different results for the same JS value depending on the compiler. Use == to check for equality of two JS-typed values instead, but do not check for equality between a Dart value and a JS-typed value.

Classes#

Class	Description
JS	An annotation on a JavaScript interop declaration.
JSExport	Annotation to allow Dart classes to be wrapped with a JS object using `dart:js_interop` 's `createJSInteropWrapper` .

Exceptions#

Exception	Description
NullRejectionException	Exception for when a JSPromise that is converted via JSPromiseToFuture.toDart is rejected with a `null` or `undefined` value.

Extensions#

Extension	on	Description
BoolToJSBoolean	bool	Conversions from bool to JSBoolean .
ByteBufferToJSArrayBuffer	ByteBuffer	Conversions from ByteBuffer to JSArrayBuffer .
ByteDataToJSDataView	ByteData	Conversions from ByteData to JSDataView .
DoubleToJSNumber	double	Conversions from double to JSNumber .
ExternalDartReferenceToObject<T extends Object?>	ExternalDartReference<T>	Conversions from ExternalDartReference to the value of type `T` .
Float32ListToJSFloat32Array	Float32List	Conversions from Float32List to JSFloat32Array .
Float64ListToJSFloat64Array	Float64List	Conversions from Float64List to JSFloat64Array .
FunctionToJSExportedDartFunction	Function	Conversions from Function to JSExportedDartFunction .
FutureOfJSAnyToJSPromise<T extends JSAny?>	Future<T>	Conversions from Future to JSPromise where the Future returns a value.
FutureOfVoidToJSPromise	Future<void>	Conversions from Future to JSPromise where the Future does not return a value.
Int16ListToJSInt16Array	Int16List	Conversions from Int16List to JSInt16Array .
Int32ListToJSInt32Array	Int32List	Conversions from Int32List to JSInt32Array .
Int8ListToJSInt8Array	Int8List	Conversions from Int8List to JSInt8Array .
JSAnyOperatorExtension	JSAny?	General-purpose JavaScript operators.
JSAnyUtilityExtension	JSAny?	Common utility functions that are useful for any JavaScript value.
JSArrayBufferToByteBuffer	JSArrayBuffer	Conversions from JSArrayBuffer to ByteBuffer .
JSArrayToList<T extends JSAny?>	JSArray<T>	Conversions from JSArray to List .
JSBooleanToBool	JSBoolean	Conversions from JSBoolean to bool .
JSBoxedDartObjectToObject	JSBoxedDartObject	Conversions from JSBoxedDartObject to Object .
JSDataViewToByteData	JSDataView	Conversions from JSDataView to ByteData .
JSExportedDartFunctionToFunction	JSExportedDartFunction	Conversions from JSExportedDartFunction to Function .
JSFloat32ArrayToFloat32List	JSFloat32Array	Conversions from JSFloat32Array to Float32List .
JSFloat64ArrayToFloat64List	JSFloat64Array	Conversions from JSFloat64Array to Float64List .
JSFunctionUtilExtension	JSFunction	Utility extensions for JSFunction .
JSInt16ArrayToInt16List	JSInt16Array	Conversions from JSInt16Array to Int16List .
JSInt32ArrayToInt32List	JSInt32Array	Conversions from JSInt32Array to Int32List .
JSInt8ArrayToInt8List	JSInt8Array	Conversions from JSInt8Array to Int8List .
JSNumberToNumber	JSNumber	Conversions from JSNumber to double or int .
JSPromiseToFuture<T extends JSAny?>	JSPromise<T>	Conversions from JSPromise to Future .
JSStringToString	JSString	Conversions from JSString to String .
JSUint16ArrayToUint16List	JSUint16Array	Conversions from JSUint16Array to Uint16List .
JSUint32ArrayToUint32List	JSUint32Array	Conversions from JSUint32Array to Uint32List .
JSUint8ArrayToUint8List	JSUint8Array	Conversions from JSUint8Array to Uint8List .
JSUint8ClampedArrayToUint8ClampedList	JSUint8ClampedArray	Conversions from JSUint8ClampedArray to Uint8ClampedList .
ListToJSArray<T extends JSAny?>	List<T>	Conversions from List to JSArray .
NullableObjectUtilExtension	Object?	Common utility functions for <code> Object ?</code>s.
NullableUndefineableJSAnyExtension	JSAny?	Helper members to determine if a value is JavaScript `undefined` or `null`.
NumToJSExtension	num	Conversions from num to JSNumber .
ObjectToExternalDartReference<T extends Object?>	T	Conversions from a value of type `T` to ExternalDartReference .
ObjectToJSBoxedDartObject	Object	Conversions from Object to JSBoxedDartObject .
StringToJSString	String	Conversions from String to JSString .
Uint16ListToJSUint16Array	Uint16List	Conversions from Uint16List to JSUint16Array .
Uint32ListToJSUint32Array	Uint32List	Conversions from Uint32List to JSUint32Array .
Uint8ClampedListToJSUint8ClampedArray	Uint8ClampedList	Conversions from Uint8ClampedList to JSUint8ClampedArray .
Uint8ListToJSUint8Array	Uint8List	Conversions from Uint8List to JSUint8Array .

Extension Types#

Extension Type	Description
ExternalDartReference<T extends Object?>	An opaque reference to a Dart object that can be passed to JavaScript.
JSAny	A non-nullish JavaScript value.
JSArray<T extends JSAny?>	A JavaScript `Array`.
JSArrayBuffer	A JavaScript `ArrayBuffer`.
JSBigInt	A JavaScript `BigInt` .
JSBoolean	A JavaScript boolean.
JSBoxedDartObject	A Dart object that is wrapped with a JavaScript object so that it can be passed to JavaScript safely.
JSDataView	A JavaScript `DataView`.
JSExportedDartFunction	A JavaScript callable function created from a Dart function.
JSFloat32Array	A JavaScript `Float32Array`.
JSFloat64Array	A JavaScript `Float64Array`.
JSFunction	A JavaScript `Function` value.
JSInt16Array	A JavaScript `Int16Array` .
JSInt32Array	A JavaScript `Int32Array` .
JSInt8Array	A JavaScript `Int8Array` .
JSNumber	A JavaScript number.
JSObject	A JavaScript `Object`.
JSPromise<T extends JSAny?>	A JavaScript `Promise` or a promise-like object.
JSString	A JavaScript string.
JSSymbol	A JavaScript `Symbol` .
JSTypedArray	Abstract supertype of all JavaScript typed arrays.
JSUint16Array	A JavaScript `Uint16Array` .
JSUint32Array	A JavaScript `Uint32Array` .
JSUint8Array	A JavaScript `Uint8Array` .
JSUint8ClampedArray	A JavaScript `Uint8ClampedArray`.

Functions#

Function	Description
createJSInteropWrapper<T extends Object>	Given a instance of a Dart class that contains an <code>@ JSExport </code> annotation, creates a JavaScript object that wraps the given Dart object.
importModule	Dynamically imports a JavaScript module with the given `moduleName` using the JavaScript `import()` syntax.

Properties#

Property	Description
globalContext	The global scope that is used to find user-declared interop members.

Constants#

Constant	Description
anonymous	An annotation that indicates a JS annotated class is structural and does not have a known JavaScript prototype.
staticInterop	staticInterop enables the JS annotated class to be treated as a "static" interop class.

Typedefs#

Typedef	Description
JSVoid	JS type equivalent for `undefined` for interop member return types.