Struct JsOption 

pub struct JsOption<T = JsValue> { /* private fields */ }

A nullable JS value of type T.

Unlike Option<T>, which is a Rust-side construct, JsOption<T> represents a JS value that may be T, null, or undefined, where the null status is not yet known in Rust. The value remains in JS until inspected via methods like is_empty, as_option, or into_option.

T must implement JsGeneric, meaning it is any type that can be represented as a JsValue (e.g., JsString, Number, Object, etc.). JsOption<T> itself implements JsGeneric, so it can be used in all generic positions that accept JS types.

Implementations

impl<T: JsGeneric> JsOption<T>

pub fn new() -> Self

pub fn wrap(val: T) -> Self

pub fn from_option(opt: Option<T>) -> Self

pub fn is_empty(&self) -> bool

pub fn as_option(&self) -> Option<T>

pub fn into_option(self) -> Option<T>

pub fn unwrap(self) -> T

pub fn expect(self, msg: &str) -> T

pub fn unwrap_or_default(self) -> T

where T: Default,

pub fn unwrap_or_else<F>(self, f: F) -> T

where F: FnOnce() -> T,

Trait Implementations

impl<T> AsRef<JsOption<T>> for JsOption<T>

fn as_ref(&self) -> &JsOption<T>

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

impl<T> AsRef<JsValue> for JsOption<T>

fn as_ref(&self) -> &JsValue

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

impl<T> BatchableResult for JsOption<T>

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

impl<T> BinaryDecode for JsOption<T>

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

impl<T> BinaryEncode for JsOption<T>

fn encode(self, encoder: &mut EncodedData)

impl<T: Clone> Clone for JsOption<T>

fn clone(&self) -> JsOption<T>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<T: JsGeneric + Debug> Debug for JsOption<T>

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

Formats the value using the given formatter.

impl<T: JsGeneric> Default for JsOption<T>

fn default() -> Self

Returns the “default value” for a type.

impl<T: JsGeneric> Deref for JsOption<T>

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &T

Dereferences the value.

impl<T: JsGeneric + Display> Display for JsOption<T>

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

Formats the value using the given formatter.

impl<T> EncodeTypeDef for JsOption<T>

fn encode_type_def(type_def: &mut TypeDef)

impl<T> ErasableGeneric for JsOption<T>

type Repr = JsValue

impl<T> From<JsOption<T>> for JsValue

fn from(val: JsOption<T>) -> Self

Converts to this type from the input type.

impl<T> From<JsValue> for JsOption<T>

fn from(val: JsValue) -> Self

Converts to this type from the input type.

impl<T: 'static> IntoJsGeneric for JsOption<T>

where JsOption<T>: JsGeneric,

type JsCanon = JsOption<T>

fn to_js(self) -> Self::JsCanon

impl<T: JsGeneric> JsCast for JsOption<T>

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<T> JsRefEncode for JsOption<T>

fn js_ref(&self) -> JsRef

impl<T: PartialEq> PartialEq for JsOption<T>

fn eq(&self, other: &JsOption<T>) -> 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<T> Promising for JsOption<T>

type Resolution = JsOption<T>

impl<T> StructuralPartialEq for JsOption<T>

impl<T> UpcastFrom<()> for JsOption<T>

impl<T1, T2, Target1, Target2> UpcastFrom<(T1, T2)> for JsOption<(Target1, Target2)>

where T1: JsGeneric, T2: JsGeneric, Target1: JsGeneric + UpcastFrom<T1>, Target2: JsGeneric + UpcastFrom<T2>,

impl<T1, T2, T3, Target1, Target2, Target3> UpcastFrom<(T1, T2, T3)> for JsOption<(Target1, Target2, Target3)>

where T1: JsGeneric, T2: JsGeneric, T3: JsGeneric, Target1: JsGeneric + UpcastFrom<T1>, Target2: JsGeneric + UpcastFrom<T2>, Target3: JsGeneric + UpcastFrom<T3>,

impl<T1, T2, T3, T4, Target1, Target2, Target3, Target4> UpcastFrom<(T1, T2, T3, T4)> for JsOption<(Target1, Target2, Target3, Target4)>

where T1: JsGeneric, T2: JsGeneric, T3: JsGeneric, T4: JsGeneric, Target1: JsGeneric + UpcastFrom<T1>, Target2: JsGeneric + UpcastFrom<T2>, Target3: JsGeneric + UpcastFrom<T3>, Target4: JsGeneric + UpcastFrom<T4>,

impl<T1, T2, T3, T4, T5, Target1, Target2, Target3, Target4, Target5> UpcastFrom<(T1, T2, T3, T4, T5)> for JsOption<(Target1, Target2, Target3, Target4, Target5)>

where T1: JsGeneric, T2: JsGeneric, T3: JsGeneric, T4: JsGeneric, T5: JsGeneric, Target1: JsGeneric + UpcastFrom<T1>, Target2: JsGeneric + UpcastFrom<T2>, Target3: JsGeneric + UpcastFrom<T3>, Target4: JsGeneric + UpcastFrom<T4>, Target5: JsGeneric + UpcastFrom<T5>,

impl<T1, T2, T3, T4, T5, T6, Target1, Target2, Target3, Target4, Target5, Target6> UpcastFrom<(T1, T2, T3, T4, T5, T6)> for JsOption<(Target1, Target2, Target3, Target4, Target5, Target6)>

where T1: JsGeneric, T2: JsGeneric, T3: JsGeneric, T4: JsGeneric, T5: JsGeneric, T6: JsGeneric, Target1: JsGeneric + UpcastFrom<T1>, Target2: JsGeneric + UpcastFrom<T2>, Target3: JsGeneric + UpcastFrom<T3>, Target4: JsGeneric + UpcastFrom<T4>, Target5: JsGeneric + UpcastFrom<T5>, Target6: JsGeneric + UpcastFrom<T6>,

impl<T1, T2, T3, T4, T5, T6, T7, Target1, Target2, Target3, Target4, Target5, Target6, Target7> UpcastFrom<(T1, T2, T3, T4, T5, T6, T7)> for JsOption<(Target1, Target2, Target3, Target4, Target5, Target6, Target7)>

where T1: JsGeneric, T2: JsGeneric, T3: JsGeneric, T4: JsGeneric, T5: JsGeneric, T6: JsGeneric, T7: JsGeneric, Target1: JsGeneric + UpcastFrom<T1>, Target2: JsGeneric + UpcastFrom<T2>, Target3: JsGeneric + UpcastFrom<T3>, Target4: JsGeneric + UpcastFrom<T4>, Target5: JsGeneric + UpcastFrom<T5>, Target6: JsGeneric + UpcastFrom<T6>, Target7: JsGeneric + UpcastFrom<T7>,

impl<T1, T2, T3, T4, T5, T6, T7, T8, Target1, Target2, Target3, Target4, Target5, Target6, Target7, Target8> UpcastFrom<(T1, T2, T3, T4, T5, T6, T7, T8)> for JsOption<(Target1, Target2, Target3, Target4, Target5, Target6, Target7, Target8)>

where T1: JsGeneric, T2: JsGeneric, T3: JsGeneric, T4: JsGeneric, T5: JsGeneric, T6: JsGeneric, T7: JsGeneric, T8: JsGeneric, Target1: JsGeneric + UpcastFrom<T1>, Target2: JsGeneric + UpcastFrom<T2>, Target3: JsGeneric + UpcastFrom<T3>, Target4: JsGeneric + UpcastFrom<T4>, Target5: JsGeneric + UpcastFrom<T5>, Target6: JsGeneric + UpcastFrom<T6>, Target7: JsGeneric + UpcastFrom<T7>, Target8: JsGeneric + UpcastFrom<T8>,

impl<T1, Target1> UpcastFrom<(T1,)> for JsOption<(Target1,)>

where T1: JsGeneric, Target1: JsGeneric + UpcastFrom<T1>,

impl<T> UpcastFrom<JsOption<T>> for JsValue

impl<T, U> UpcastFrom<JsOption<U>> for JsOption<T>

where T: UpcastFrom<U>,

impl UpcastFrom<JsValue> for JsOption<JsValue>

impl<T> UpcastFrom<Null> for JsOption<T>

impl<T> UpcastFrom<Undefined> for JsOption<T>