Struct sauron::prelude::JsValue [−][src]
pub struct JsValue { /* fields omitted */ }
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
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.
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.
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.
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.
Creates a new JsValue
from the JSON serialization of the object t
provided.
This function will serialize the provided value t
to a JSON string,
send the JSON string to JS, parse it into a JS object, and then return
a handle to the JS object. This is unlikely to be super speedy so it’s
not recommended for large payloads, but it’s a nice to have in some
situations!
Usage of this API requires activating the serde-serialize
feature of
the wasm-bindgen
crate.
Errors
Returns any error encountered when serializing T
into JSON.
Invokes JSON.stringify
on this value and then parses the resulting
JSON into an arbitrary Rust value.
This function will first call JSON.stringify
on the JsValue
itself.
The resulting string is then passed into Rust which then parses it as
JSON into the resulting value.
Usage of this API requires activating the serde-serialize
feature of
the wasm-bindgen
crate.
Errors
Returns any error encountered when parsing the JSON into a T
.
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
.
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.
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
.
Tests whether this JS value is undefined
Tests whether the type of this JS value is function
.
Trait Implementations
Performs the conversion.
Performs the conversion.
Performs the conversion.
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Performs the conversion.
Performs a dynamic instanceof
check to see whether the JsValue
provided is an instance of this type. Read more
Performs a zero-cost unchecked conversion from a JsValue
into an
instance of Self
Read more
Performs a zero-cost unchecked conversion from a &JsValue
into an
instance of &Self
. Read more
Test whether this JS value has a type T
. Read more
Performs a dynamic cast (checked at runtime) of this value into the
target type T
. Read more
Performs a dynamic cast (checked at runtime) of this value into the
target type T
. Read more
Performs a zero-cost unchecked cast into the specified type. Read more
Performs a zero-cost unchecked cast into a reference to the specified type. Read more
Test whether this JS value is an instance of the type T
. Read more
Performs a dynamic check to see whether the JsValue
provided
is a value of this type. Read more
type Anchor = ManuallyDrop<JsValue>
type Anchor = ManuallyDrop<JsValue>
The type that holds the reference to 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. Read more
Recover a Self::Anchor
from Self::Abi
. Read more
Auto Trait Implementations
impl RefUnwindSafe for JsValue
impl UnwindSafe for JsValue
Blanket Implementations
Mutably borrows from an owned value. Read more
type Abi = <T as IntoWasmAbi>::Abi
type Abi = <T as IntoWasmAbi>::Abi
Same as IntoWasmAbi::Abi
Same as IntoWasmAbi::into_abi
, except that it may throw and never
return in the case of Err
. Read more