Struct Undefined

pub struct Undefined { /* private fields */ }

The struct merely carries the underlying emlite::Val so it can be passed through JS APIs; there is only one meaningful instance, exposed as Undefined::VALUE.

Implementations

impl Undefined

pub const VALUE: Undefined

The canonical undefined value.

Because undefined has no runtime state, storing a single constant is sufficient and avoids repeated Val::undefined() calls.

pub fn is_null(&self) -> bool

Always returns false — undefined is never null.

pub fn is_undefined(&self) -> bool

Always returns true.

Methods from Deref<Target = Val>

pub fn get<T>(&self, prop: T) -> Val

where T: Into<Val>,

Gets the property prop

pub fn set<K, V>(&self, prop: K, val: V)

where K: Into<Val>, V: Into<Val>,

Set the underlying js object property prop to val

pub fn has<T>(&self, prop: T) -> bool

where T: Into<Val>,

Checks whether a property prop exists

pub fn has_own_property(&self, prop: &str) -> bool

Checks whether a non-inherited property prop exists

pub fn type_of(&self) -> String

Gets the typeof the underlying js object

pub fn at<T>(&self, idx: T) -> Val

where T: Into<Val>,

Gets the element at index idx. Assumes the underlying js type is indexable

pub fn to_vec<V>(&self) -> Vec<V>

where V: FromVal,

Converts the underlying js array to a Vec of V

pub fn call(&self, f: &str, args: &[Val]) -> Val

Calls the method f with args, can return an undefined js value

pub fn new(&self, args: &[Val]) -> Val

Calls the object’s constructor with args constructing a new object

pub fn invoke(&self, args: &[Val]) -> Val

Invokes the function object with args, can return an undefined js value

pub fn await_(&self) -> Val

Awaits the invoked function object

pub fn instanceof(&self, v: Val) -> bool

Checks whether this Val is an instanceof v

pub fn is_number(&self) -> bool

pub fn is_string(&self) -> bool

pub fn is_null(&self) -> bool

pub fn is_undefined(&self) -> bool

pub fn is_error(&self) -> bool

pub fn is_function(&self) -> bool

pub fn as_<T>(&self) -> T

where T: FromVal,

Trait Implementations

impl AsMut<Val> for Undefined

fn as_mut(&mut self) -> &mut Val

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

impl AsRef<Val> for Undefined

fn as_ref(&self) -> &Val

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

impl Clone for Undefined

fn clone(&self) -> Undefined

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Undefined

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

Formats the value using the given formatter.

impl Deref for Undefined

type Target = Val

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl DerefMut for Undefined

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.

impl DynCast for Undefined

fn instanceof(_val: &Val) -> bool

Implementation of val instanceof ThisType.

fn unchecked_from_val(v: Val) -> Self

Zero-cost unchecked conversion from Val into Self.

fn unchecked_from_val_ref(v: &Val) -> &Self

Zero-cost unchecked conversion from &Val into &Self.

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

where T: DynCast,

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

where T: DynCast,

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

where T: DynCast,

fn unchecked_into<T>(self) -> T

where T: DynCast,

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

where T: DynCast,

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

where T: DynCast,

fn is_type_of(val: &Val) -> bool

Customisable brand check – defaults to instanceof.

impl From<&Undefined> for Val

fn from(x: &Undefined) -> Val

Converts to this type from the input type.

impl From<Undefined> for Val

fn from(x: Undefined) -> Val

Converts to this type from the input type.

impl FromVal for Undefined

fn from_val(v: &Val) -> Self

Creates a Val object from another

fn take_ownership(v: Handle) -> Self

Takes the ownership of a handle

fn as_handle(&self) -> Handle

Returns the raw js handle