Struct JsNullable

Source

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

Expand description

A nullable JS value of type T.

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

This models WebIDL nullable types (T?). Following WebIDL’s ECMAScript conversion rules, where undefined coerces to null at nullable positions, both null and undefined are treated as absent. The canonical empty value produced from Rust is null.

For TypeScript-style T | undefined with strict undefined-only emptiness, use JsOption<T> instead.

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

Struct JsNullable Copy item path

Implementations§

impl<T> JsNullable<T>where T: JsGeneric,

pub fn new() -> JsNullable<T>

pub fn wrap(val: T) -> JsNullable<T>

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

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

§Panics

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

§Panics

pub fn unwrap_or_default(self) -> Twhere T: Default,

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

Methods from Deref<Target = JsValue>§

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

pub fn is_string(&self) -> bool

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

§UTF-16 vs UTF-8

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

pub fn is_null(&self) -> bool

pub fn is_undefined(&self) -> bool

pub fn is_null_or_undefined(&self) -> bool

pub fn is_symbol(&self) -> bool

pub fn is_object(&self) -> bool

pub fn is_array(&self) -> bool

pub fn is_function(&self) -> bool

pub fn is_bigint(&self) -> bool

pub fn js_typeof(&self) -> JsValue

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

pub fn is_truthy(&self) -> bool

pub fn is_falsy(&self) -> bool

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

pub fn bit_not(&self) -> JsValue

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

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

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

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

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

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

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

pub fn unchecked_into_f64(&self) -> f64

Trait Implementations§

impl<T> AsRef<JsNullable<T>> for JsNullable<T>

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

impl<T> AsRef<JsValue> for JsNullable<T>

fn as_ref(&self) -> &JsValue

impl<T> Clone for JsNullable<T>where T: Clone,

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

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

impl<T> Debug for JsNullable<T>where T: JsGeneric + Debug,

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

impl<T> Default for JsNullable<T>where T: JsGeneric,

fn default() -> JsNullable<T>

impl<T> Deref for JsNullable<T>

type Target = JsValue

fn deref(&self) -> &JsValue

impl<T> Display for JsNullable<T>where T: JsGeneric + Display,

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

impl<T> ErasableGeneric for JsNullable<T>

type Repr = JsValue

impl From<JsValue> for JsNullable

fn from(obj: JsValue) -> JsNullable

impl<T> From<Nullable<T>> for JsNullable<T>where T: JsGeneric,

fn from(nullable: Nullable<T>) -> JsNullable<T>

impl<T> From<Option<Nullable<T>>> for JsNullable<T>where T: JsGeneric,

fn from(option: Option<Nullable<T>>) -> JsNullable<T>

impl<T> FromWasmAbi for JsNullable<T>

type Abi = <JsValue as FromWasmAbi>::Abi

unsafe fn from_abi(js: <JsNullable<T> as FromWasmAbi>::Abi) -> JsNullable<T>

impl<T> IntoJsGeneric for JsNullable<T>where JsNullable<T>: JsGeneric,

type JsCanon = JsNullable<T>

fn to_js(self) -> JsNullable<T>

impl<T> IntoWasmAbi for JsNullable<T>

type Abi = <JsValue as IntoWasmAbi>::Abi

fn into_abi(self) -> <JsNullable<T> as IntoWasmAbi>::Abi

impl<'__wbg_ref, T> IntoWasmAbi for &'__wbg_ref JsNullable<T>

type Abi = <&'__wbg_ref JsValue as IntoWasmAbi>::Abi

fn into_abi(self) -> <&'__wbg_ref JsNullable<T> as IntoWasmAbi>::Abi

Struct JsNullable

impl<T> JsNullable<T>
where T: JsGeneric,

pub fn unwrap_or_default(self) -> T
where T: Default,

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

impl<T> Clone for JsNullable<T>
where T: Clone,

impl<T> Debug for JsNullable<T>
where T: JsGeneric + Debug,

impl<T> Default for JsNullable<T>
where T: JsGeneric,

impl<T> Display for JsNullable<T>
where T: JsGeneric + Display,

impl<T> From<Nullable<T>> for JsNullable<T>
where T: JsGeneric,

impl<T> From<Option<Nullable<T>>> for JsNullable<T>
where T: JsGeneric,

impl<T> IntoJsGeneric for JsNullable<T>
where JsNullable<T>: JsGeneric,

fn has_type<T>(&self) -> bool
where T: JsCast,

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

fn dyn_ref<T>(&self) -> Option<&T>
where T: JsCast,

fn unchecked_into<T>(self) -> T
where T: JsCast,

fn unchecked_ref<T>(&self) -> &T
where T: JsCast,

fn is_instance_of<T>(&self) -> bool
where T: JsCast,

impl<T1, T2, Target1, Target2> UpcastFrom<(T1, T2)> for JsNullable<(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 JsNullable<(Target1, Target2, Target3)>
where T1: JsGeneric, T2: JsGeneric, T3: JsGeneric, Target1: JsGeneric + UpcastFrom<T1>, Target2: JsGeneric + UpcastFrom<T2>, Target3: JsGeneric + UpcastFrom<T3>,

impl<T1, Target1> UpcastFrom<(T1,)> for JsNullable<(Target1,)>
where T1: JsGeneric, Target1: JsGeneric + UpcastFrom<T1>,

impl<T, Target> UpcastFrom<const T> for JsNullable<const Target>
where Target: UpcastFrom<T>,

impl<T, UpcastTarget0> UpcastFrom<Array<T>> for JsNullable<Array<UpcastTarget0>>
where __UpcastTarget0: UpcastFrom<T>,