Struct p5_sys::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

impl JsValue[src]

pub const NULL: JsValue[src]

The null JS value constant.

pub const UNDEFINED: JsValue[src]

The undefined JS value constant.

pub const TRUE: JsValue[src]

The true JS value constant.

pub const FALSE: JsValue[src]

The false JS value constant.

pub fn from_str(s: &str) -> JsValue[src]

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.

pub fn from_f64(n: f64) -> JsValue[src]

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.

pub fn from_bool(b: bool) -> JsValue[src]

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.

pub fn undefined() -> JsValue[src]

Creates a new JS value representing undefined.

pub fn null() -> JsValue[src]

Creates a new JS value representing null.

pub fn symbol(description: Option<&str>) -> JsValue[src]

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.

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

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.

pub fn is_string(&self) -> bool[src]

Tests whether this JS value is a JS string.

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

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.

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

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.

pub fn is_null(&self) -> bool[src]

Tests whether this JS value is null

pub fn is_undefined(&self) -> bool[src]

Tests whether this JS value is undefined

pub fn is_symbol(&self) -> bool[src]

Tests whether the type of this JS value is symbol

pub fn is_object(&self) -> bool[src]

Tests whether typeof self == "object" && self !== null.

pub fn is_function(&self) -> bool[src]

Tests whether the type of this JS value is function.

pub fn is_truthy(&self) -> bool[src]

Tests whether the value is “truthy”.

pub fn is_falsy(&self) -> bool[src]

Tests whether the value is “falsy”.

Trait Implementations

impl AsRef<JsValue> for JsValue[src]

pub fn as_ref(&self) -> &JsValue[src]

Performs the conversion.

impl<T> AsRef<JsValue> for Closure<T> where
    T: ?Sized,

[src]

pub fn as_ref(&self) -> &JsValue[src]

Performs the conversion.

impl AsRef<JsValue> for SoundFile[src]