Struct wasm_bindgen::JsValue
source · pub struct JsValue { /* private fields */ }
Expand description
Representation of an object owned by JS.
A JsValue
doesn’t actually live in Rust right now but actually in a table
owned by the wasm-bindgen
generated JS glue code. Eventually the ownership
will transfer into wasm directly and this will likely become more efficient,
but for now it may be slightly slow.
Implementations§
source§impl JsValue
impl JsValue
sourcepub fn from_str(s: &str) -> JsValue
pub fn from_str(s: &str) -> JsValue
Creates a new JS value which is a string.
The utf-8 string provided is copied to the JS heap and the string will be owned by the JS garbage collector.
sourcepub fn from_f64(n: f64) -> JsValue
pub fn from_f64(n: f64) -> JsValue
Creates a new JS value which is a number.
This function creates a JS value representing a number (a heap allocated number) and returns a handle to the JS version of it.
sourcepub fn bigint_from_str(s: &str) -> JsValue
pub fn bigint_from_str(s: &str) -> JsValue
Creates a new JS value which is a bigint from a string representing a number.
This function creates a JS value representing a bigint (a heap allocated large integer) and returns a handle to the JS version of it.
sourcepub const fn from_bool(b: bool) -> JsValue
pub const fn from_bool(b: bool) -> JsValue
Creates a new JS value which is a boolean.
This function creates a JS object representing a boolean (a heap allocated boolean) and returns a handle to the JS version of it.
sourcepub fn symbol(description: Option<&str>) -> JsValue
pub fn symbol(description: Option<&str>) -> JsValue
Creates a new JS symbol with the optional description specified.
This function will invoke the Symbol
constructor in JS and return the
JS object corresponding to the symbol created.
sourcepub fn as_f64(&self) -> Option<f64>
pub fn as_f64(&self) -> Option<f64>
Returns the f64
value of this JS value if it’s an instance of a
number.
If this JS value is not an instance of a number then this returns
None
.
sourcepub fn as_string(&self) -> Option<String>
pub fn as_string(&self) -> Option<String>
If this JS value is a string value, this function copies the JS string
value into wasm linear memory, encoded as UTF-8, and returns it as a
Rust String
.
To avoid the copying and re-encoding, consider the
JsString::try_from()
function from js-sys
instead.
If this JS value is not an instance of a string or if it’s not valid
utf-8 then this returns None
.
UTF-16 vs UTF-8
JavaScript strings in general are encoded as UTF-16, but Rust strings
are encoded as UTF-8. This can cause the Rust string to look a bit
different than the JS string sometimes. For more details see the
documentation about the str
type which contains a few
caveats about the encodings.
sourcepub fn as_bool(&self) -> Option<bool>
pub fn as_bool(&self) -> Option<bool>
Returns the bool
value of this JS value if it’s an instance of a
boolean.
If this JS value is not an instance of a boolean then this returns
None
.
sourcepub fn is_undefined(&self) -> bool
pub fn is_undefined(&self) -> bool
Tests whether this JS value is undefined
sourcepub fn is_function(&self) -> bool
pub fn is_function(&self) -> bool
Tests whether the type of this JS value is function
.
sourcepub fn js_in(&self, obj: &JsValue) -> bool
pub fn js_in(&self, obj: &JsValue) -> bool
Applies the binary in
JS operator on the two JsValue
s.
sourcepub fn loose_eq(&self, other: &Self) -> bool
pub fn loose_eq(&self, other: &Self) -> bool
Compare two JsValue
s for equality, using the ==
operator in JS.
sourcepub fn unsigned_shr(&self, rhs: &Self) -> u32
pub fn unsigned_shr(&self, rhs: &Self) -> u32
Applies the binary >>>
JS operator on the two JsValue
s.
sourcepub fn checked_div(&self, rhs: &Self) -> Self
pub fn checked_div(&self, rhs: &Self) -> Self
Applies the binary /
JS operator on two JsValue
s, catching and returning any RangeError
thrown.
sourcepub fn unchecked_into_f64(&self) -> f64
pub fn unchecked_into_f64(&self) -> f64
Applies the unary +
JS operator on a JsValue
. Can throw.
Trait Implementations§
source§impl FromWasmAbi for JsValue
impl FromWasmAbi for JsValue
source§impl<'a> IntoWasmAbi for &'a JsValue
impl<'a> IntoWasmAbi for &'a JsValue
source§impl IntoWasmAbi for JsValue
impl IntoWasmAbi for JsValue
source§impl JsCast for JsValue
impl JsCast for JsValue
source§fn instanceof(_val: &JsValue) -> bool
fn instanceof(_val: &JsValue) -> bool
instanceof
check to see whether the JsValue
provided is an instance of this type. Read moresource§fn unchecked_from_js(val: JsValue) -> Self
fn unchecked_from_js(val: JsValue) -> Self
source§fn unchecked_from_js_ref(val: &JsValue) -> &Self
fn unchecked_from_js_ref(val: &JsValue) -> &Self
source§fn has_type<T>(&self) -> boolwhere
T: JsCast,
fn has_type<T>(&self) -> boolwhere T: JsCast,
T
. Read moresource§fn dyn_into<T>(self) -> Result<T, Self>where
T: JsCast,
fn dyn_into<T>(self) -> Result<T, Self>where T: JsCast,
T
. Read moresource§fn dyn_ref<T>(&self) -> Option<&T>where
T: JsCast,
fn dyn_ref<T>(&self) -> Option<&T>where T: JsCast,
T
. Read moresource§fn unchecked_into<T>(self) -> Twhere
T: JsCast,
fn unchecked_into<T>(self) -> Twhere T: JsCast,
source§fn unchecked_ref<T>(&self) -> &Twhere
T: JsCast,
fn unchecked_ref<T>(&self) -> &Twhere T: JsCast,
source§impl LongRefFromWasmAbi for JsValue
impl LongRefFromWasmAbi for JsValue
source§impl<'a> PartialEq<&'a String> for JsValue
impl<'a> PartialEq<&'a String> for JsValue
source§impl<'a> PartialEq<&'a str> for JsValue
impl<'a> PartialEq<&'a str> for JsValue
source§impl PartialEq<String> for JsValue
impl PartialEq<String> for JsValue
source§impl PartialEq<bool> for JsValue
impl PartialEq<bool> for JsValue
source§impl PartialEq<i128> for JsValue
impl PartialEq<i128> for JsValue
source§impl PartialEq<isize> for JsValue
impl PartialEq<isize> for JsValue
source§impl PartialEq<u128> for JsValue
impl PartialEq<u128> for JsValue
source§impl PartialEq<usize> for JsValue
impl PartialEq<usize> for JsValue
source§impl PartialEq<JsValue> for JsValue
impl PartialEq<JsValue> for JsValue
source§impl RefFromWasmAbi for JsValue
impl RefFromWasmAbi for JsValue
§type Anchor = ManuallyDrop<JsValue>
type Anchor = ManuallyDrop<JsValue>
Self
for the duration of the
invocation of the function that has an &Self
parameter. This is
required to ensure that the lifetimes don’t persist beyond one function
call, and so that they remain anonymous.Auto Trait Implementations§
impl RefUnwindSafe for JsValue
impl !Send for JsValue
impl !Sync for JsValue
impl Unpin for JsValue
impl UnwindSafe for JsValue
Blanket Implementations§
source§impl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere T: ?Sized,
source§fn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
source§impl<T> ReturnWasmAbi for Twhere
T: IntoWasmAbi,
impl<T> ReturnWasmAbi for Twhere T: IntoWasmAbi,
§type Abi = <T as IntoWasmAbi>::Abi
type Abi = <T as IntoWasmAbi>::Abi
IntoWasmAbi::Abi
source§fn return_abi(self) -> <T as ReturnWasmAbi>::Abi
fn return_abi(self) -> <T as ReturnWasmAbi>::Abi
IntoWasmAbi::into_abi
, except that it may throw and never
return in the case of Err
.