dart:js_util library

Utility methods to manipulate package:js annotated JavaScript interop objects in cases where the name to call is not known at runtime.

Note

You should usually use dart:js_interop instead of this library. To learn more, check out the JS interop documentation.

You should only use these methods when the same effect cannot be achieved with @JS() annotations.

Properties

globalThis → Object
no setter
objectPrototype → Object?
Returns the Object prototype. Equivalent to Object.prototype.
no setter

Functions

add<T>(Object? first, Object? second) → T
Perform JavaScript addition (+) on two values.
allowInterop<F extends Function>(F f) → F
Returns a wrapper around function f that can be called from JavaScript using package:js JavaScript interop.
allowInteropCaptureThis(Function f) → Function
Returns a wrapper around function f that can be called from JavaScript using package:js JavaScript interop, passing JavaScript this as the first argument.
and<T>(Object? first, Object? second) → T
Perform JavaScript logical and comparison (&&) of two expressions.
callConstructor<T>(Object constr, List<Object?>? arguments) → T
callMethod<T>(Object o, Object method, List<Object?> args) → T
createDartExport<T extends Object>(T dartObject) → Object
Given a Dart object that is marked exportable, creates a JS object literal that forwards to that Dart class. Look at the @JSExport annotation to determine what constitutes "exportable" for a Dart class. The object literal will be a map of export names (which are either the written instance member names or their rename) to their respective Dart instance members.
createStaticInteropMock<T extends Object, U extends Object>(U dartMock, [Object? proto = null]) → T
Given a @staticInterop type T and an instance dartMock of a Dart class U that implements the external extension members of T, creates a forwarding mock.
dartify(Object? o) → Object?
Effectively the inverse of jsify, dartify Takes a JavaScript object, and converts it to a Dart based object. Only JS primitives, arrays, or 'map' like JS objects are supported.
delete<T>(Object o, Object property) → bool
Perform JavaScript delete operator (delete) on the given property of the given object.
divide<T>(Object? first, Object? second) → T
Perform JavaScript division (/) on two values.
equal<T>(Object? first, Object? second) → bool
Perform JavaScript equality comparison (==) on two values.
exponentiate<T>(Object? first, Object? second) → T
Perform JavaScript exponentiation (**) on two values.
getProperty<T>(Object o, Object name) → T
greaterThan<T>(Object? first, Object? second) → bool
Perform JavaScript greater than comparison (>) of two values.
greaterThanOrEqual<T>(Object? first, Object? second) → bool
Perform JavaScript greater than or equal comparison (>=) of two values.
hasProperty(Object o, Object name) → bool
instanceof(Object? o, Object type) → bool
Check whether o is an instance of type.
instanceOfString(Object? element, String objectType) → bool
Like instanceof only takes a String for the object name instead of a constructor object.
isJavaScriptArray(dynamic value) → bool
Returns true if a given object is a JavaScript array.
isJavaScriptSimpleObject(dynamic value) → bool
Returns true if a given object is a simple JavaScript object.
isTruthy<T>(Object? o) → bool
Determines if the given object is truthy or falsy.
jsify(Object? object) → dynamic
Recursively converts a JSON-like collection to JavaScript compatible representation.
lessThan<T>(Object? first, Object? second) → bool
Perform JavaScript less than comparison (<) of two values.
lessThanOrEqual<T>(Object? first, Object? second) → bool
Perform JavaScript less than or equal comparison (<=) of two values.
modulo<T>(Object? first, Object? second) → T
Perform JavaScript remainder (%) on two values.
multiply<T>(Object? first, Object? second) → T
Perform JavaScript multiplication (*) on two values.
newObject<T>() → T
not<T>(Object? o) → T
Perform JavaScript logical not (!) on the given object.
notEqual<T>(Object? first, Object? second) → bool
Perform JavaScript inequality comparison (!=) on two values.
objectGetPrototypeOf(Object? object) → Object?
Returns the prototype of a given object. Equivalent to Object.getPrototypeOf.
objectKeys(Object? object) → List<Object?>
Returns the keys for a given object. Equivalent to Object.keys(object).
or<T>(Object? first, Object? second) → T
Perform JavaScript logical or comparison (||) of two expressions.
promiseToFuture<T>(Object jsPromise) → Future<T>
Converts a JavaScript Promise to a Dart Future.
setProperty<T>(Object o, Object name, T? value) → T
strictEqual<T>(Object? first, Object? second) → bool
Perform JavaScript strict equality comparison (===) on two values.
strictNotEqual<T>(Object? first, Object? second) → bool
Perform JavaScript strict inequality comparison (!==) on two values.
subtract<T>(Object? first, Object? second) → T
Perform JavaScript subtraction (-) on two values.
typeofEquals<T>(Object? o, String type) → bool
Perform JavaScript typeof operator on the given object and determine if the result is equal to the given type. Exposes the whole typeof equal expression to maximize browser optimization.
unsignedRightShift(Object? leftOperand, Object? rightOperand) → num
Perform JavaScript unsigned right shift operator (>>>) on the given left operand by the amount specified by the given right operand.

Exceptions / Errors

NullRejectionException
Exception for when the promise is rejected with a null or undefined value.