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: JsGeneric> JsNullable<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

§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 into_serde<T>(&self) -> Result<T>where T: for<'a> Deserialize<'a>,

§Errors

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: &Self) -> bool

pub fn bit_not(&self) -> JsValue

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

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

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

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

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

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

pub fn gt(&self, other: &Self) -> 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> Clone for JsNullable<T>

fn clone(&self) -> Self

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

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

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

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

fn default() -> Self

impl<T> Deref for JsNullable<T>

type Target = JsValue

fn deref(&self) -> &JsValue

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

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

impl<T> ErasableGeneric for JsNullable<T>

type Repr = JsValue

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

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

impl<T> From<JsNullable<T>> for JsValue

fn from(obj: JsNullable<T>) -> JsValue

impl From<JsValue> for JsNullable

fn from(obj: JsValue) -> Self

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

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

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

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

impl<T> FromWasmAbi for JsNullable<T>

type Abi = <JsValue as FromWasmAbi>::Abi

unsafe fn from_abi(js: Self::Abi) -> Self

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

type JsCanon = JsNullable<T>

fn to_js(self) -> JsNullable<T>

Struct JsNullable

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

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

pub fn into_serde<T>(&self) -> Result<T>
where T: for<'a> Deserialize<'a>,

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

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

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

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

impl<T, U> UpcastFrom<JsNullable<U>> for JsNullable<T>
where T: UpcastFrom<U>,

impl<T, U> UpcastFrom<JsOption<U>> for JsNullable<T>
where T: UpcastFrom<U>,

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