Struct FinalizationRegistry 

pub struct FinalizationRegistry { /* private fields */ }

The FinalizationRegistry object lets you request a callback when an object is garbage-collected.

FinalizationRegistry provides a way to request that a cleanup callback get called at some point when an object registered with the registry has been reclaimed (garbage-collected). Cleanup callbacks are sometimes called finalizers.

Avoid where possible: cleanup callbacks should not be relied upon for anything essential. They are best used to reduce memory usage over the course of a program for objects that benefit from cleanup. Whether, when, and in what order callbacks fire is implementation-defined.

MDN documentation

Implementations

impl FinalizationRegistry

pub fn new( cleanup_callback: &Function<fn(JsValue) -> Undefined>, ) -> FinalizationRegistry

impl FinalizationRegistry

pub fn register(&self, target: &JsValue, held_value: &JsValue)

impl FinalizationRegistry

pub fn register_with_token( &self, target: &JsValue, held_value: &JsValue, unregister_token: &JsValue, )

impl FinalizationRegistry

pub fn unregister(&self, unregister_token: &JsValue) -> bool

Methods from Deref<Target = Object>

pub fn constructor(&self) -> Function

pub fn has_own_property(&self, property: &JsValue) -> bool

👎Deprecated:

Use Object::hasOwn instead.

pub fn is_prototype_of(&self, value: &JsValue) -> bool

pub fn property_is_enumerable(&self, property: &JsValue) -> bool

pub fn to_locale_string(&self) -> JsString

pub fn to_string(&self) -> JsString

pub fn to_js_string(&self) -> JsString

pub fn value_of(&self) -> Object

Methods from Deref<Target = JsValue>

pub const NULL: JsValue

pub const UNDEFINED: JsValue

pub const TRUE: JsValue

pub const FALSE: JsValue

pub fn unchecked_into_f64(&self) -> f64

Returns the value as f64 without type checking. Used by serde-wasm-bindgen for numeric conversions.

pub fn has_type<T>(&self) -> bool

where T: JsCast,

Check if this value is an instance of a specific JS type.

pub fn checked_div(&self, rhs: &JsValue) -> JsValue

Checked division.

pub fn pow(&self, rhs: &JsValue) -> JsValue

Power operation.

pub fn bit_and(&self, rhs: &JsValue) -> JsValue

Bitwise AND.

pub fn bit_or(&self, rhs: &JsValue) -> JsValue

Bitwise OR.

pub fn bit_xor(&self, rhs: &JsValue) -> JsValue

Bitwise XOR.

pub fn bit_not(&self) -> JsValue

Bitwise NOT.

pub fn shl(&self, rhs: &JsValue) -> JsValue

Left shift.

pub fn shr(&self, rhs: &JsValue) -> JsValue

Signed right shift.

pub fn unsigned_shr(&self, rhs: &JsValue) -> u32

Unsigned right shift.

pub fn add(&self, rhs: &JsValue) -> JsValue

Add.

pub fn sub(&self, rhs: &JsValue) -> JsValue

Subtract.

pub fn mul(&self, rhs: &JsValue) -> JsValue

Multiply.

pub fn div(&self, rhs: &JsValue) -> JsValue

Divide.

pub fn rem(&self, rhs: &JsValue) -> JsValue

Remainder.

pub fn neg(&self) -> JsValue

Negate.

pub fn lt(&self, other: &JsValue) -> bool

Less than comparison.

pub fn le(&self, other: &JsValue) -> bool

Less than or equal comparison.

pub fn gt(&self, other: &JsValue) -> bool

Greater than comparison.

pub fn ge(&self, other: &JsValue) -> bool

Greater than or equal comparison.

pub fn loose_eq(&self, other: &JsValue) -> bool

Loose equality (==).

pub fn is_falsy(&self) -> bool

Check if this value is a falsy value in JavaScript.

pub fn is_truthy(&self) -> bool

Check if this value is a truthy value in JavaScript.

pub fn is_object(&self) -> bool

Check if this value is an object.

pub fn is_function(&self) -> bool

Check if this value is a function.

pub fn is_string(&self) -> bool

Check if this value is a string.

pub fn is_symbol(&self) -> bool

Check if this value is a symbol.

pub fn is_bigint(&self) -> bool

Check if this value is a bigint.

pub fn is_array(&self) -> bool

Check if this value is an Array.

pub fn is_undefined(&self) -> bool

Check if this value is undefined.

pub fn is_null(&self) -> bool

Check if this value is null.

pub fn is_null_or_undefined(&self) -> bool

Check if this value is null or undefined.

pub fn js_typeof(&self) -> JsValue

Get the typeof this value as a string.

pub fn js_in(&self, obj: &JsValue) -> bool

Check if this value has a property with the given name.

pub fn as_bool(&self) -> Option<bool>

Get the value as a bool.

pub fn as_f64(&self) -> Option<f64>

Get the value as an f64.

pub fn as_string(&self) -> Option<String>

Get the value as a string.

pub fn as_debug_string(&self) -> String

Get a debug string representation of the value.

Trait Implementations

impl AsRef<FinalizationRegistry> for FinalizationRegistry

fn as_ref(&self) -> &FinalizationRegistry

Converts this type into a shared reference of the (usually inferred) input type.

impl AsRef<JsValue> for FinalizationRegistry

fn as_ref(&self) -> &JsValue

Converts this type into a shared reference of the (usually inferred) input type.

impl AsRef<Object> for FinalizationRegistry

fn as_ref(&self) -> &Object

Converts this type into a shared reference of the (usually inferred) input type.

impl BatchableResult for FinalizationRegistry

fn try_placeholder(batch: &mut Runtime<'_>) -> Option<Self>

impl BinaryDecode for FinalizationRegistry

fn decode(decoder: &mut DecodedData<'_>) -> Result<Self, DecodeError>

impl BinaryEncode for FinalizationRegistry

fn encode(self, encoder: &mut EncodedData)

impl Clone for FinalizationRegistry

fn clone(&self) -> FinalizationRegistry

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for FinalizationRegistry

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Deref for FinalizationRegistry

type Target = Object

The resulting type after dereferencing.

fn deref(&self) -> &Object

Dereferences the value.

impl EncodeTypeDef for FinalizationRegistry

fn encode_type_def(type_def: &mut TypeDef)

impl Eq for FinalizationRegistry

impl ErasableGeneric for FinalizationRegistry

type Repr = JsValue

impl From<FinalizationRegistry> for JsValue

fn from(val: FinalizationRegistry) -> Self

Converts to this type from the input type.

impl From<FinalizationRegistry> for Object

fn from(val: FinalizationRegistry) -> Object

Converts to this type from the input type.

impl From<JsValue> for FinalizationRegistry

fn from(val: JsValue) -> Self

Converts to this type from the input type.

impl IntoJsGeneric for FinalizationRegistry

where FinalizationRegistry: JsGeneric,

type JsCanon = FinalizationRegistry

fn to_js(self) -> Self::JsCanon

impl JsCast for FinalizationRegistry

fn instanceof(__val: &JsValue) -> bool

Check if a JsValue is an instance of this type.

fn unchecked_from_js(val: JsValue) -> Self

Unchecked cast from JsValue to this type.

fn unchecked_from_js_ref(val: &JsValue) -> &Self

Unchecked cast from a JsValue reference to a reference of this type.

fn is_type_of(val: &JsValue) -> bool

Performs a dynamic type check to see whether the JsValue provided is a value of this type.

fn has_type<T>(&self) -> bool

where T: JsCast,

Test whether this JS value has a type T.

fn dyn_into<T>(self) -> Result<T, Self>

where T: JsCast,

Try to cast this value to type T.

fn dyn_ref<T>(&self) -> Option<&T>

where T: JsCast,

Try to get a reference to type T from this value.

fn is_instance_of<T>(&self) -> bool

where T: JsCast,

Test whether this JS value is an instance of the type T.

fn unchecked_into<T>(self) -> T

where T: JsCast,

Unchecked cast to another type.

fn unchecked_ref<T>(&self) -> &T

where T: JsCast,

Unchecked cast to a reference of another type.

impl JsRefEncode for FinalizationRegistry

fn js_ref(&self) -> JsRef

impl PartialEq for FinalizationRegistry

fn eq(&self, other: &FinalizationRegistry) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Promising for FinalizationRegistry

type Resolution = FinalizationRegistry

impl StructuralPartialEq for FinalizationRegistry

impl UpcastFrom<FinalizationRegistry> for JsValue

impl UpcastFrom<FinalizationRegistry> for JsOption<JsValue>

impl UpcastFrom<FinalizationRegistry> for FinalizationRegistry

impl UpcastFrom<FinalizationRegistry> for JsOption<FinalizationRegistry>

impl UpcastFrom<FinalizationRegistry> for Object

impl UpcastFrom<FinalizationRegistry> for JsOption<Object>