Struct EnvironmentChain

#[repr(C, align(8))]
pub struct EnvironmentChain {
    pub _bindgen_opaque_blob: [u64; 16],
}

JS::EnvironmentChain stores a list of objects to put on the environment chain.

Internally the engine will create a non-syntactic ‘with’ environment for each of these objects. Note that ‘with’ environments aren’t optimized well so you should use this class only if you really have to.

The SupportUnscopables enum class controls whether these non-syntactic ‘with’ environments support Symbol.unscopables similar to syntactic ‘with’ statements in JS.

Passing SupportUnscopables::No is better for performance because it lets us skip the Symbol.unscopables property lookup. Some Web APIs require supporting Symbol.unscopables though. In Firefox, SupportUnscopables::Yes is used for event handlers.

Fields

_bindgen_opaque_blob: [u64; 16]

Trait Implementations

impl Clone for EnvironmentChain

fn clone(&self) -> EnvironmentChain

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for EnvironmentChain

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

Formats the value using the given formatter.

impl PartialEq for EnvironmentChain

fn eq(&self, other: &EnvironmentChain) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for EnvironmentChain

impl StructuralPartialEq for EnvironmentChain