Struct deno_core::JsRuntime [−][src]
pub struct JsRuntime { /* fields omitted */ }
Expand description
A single execution context of JavaScript. Corresponds roughly to the “Web Worker” concept in the DOM. A JsRuntime is a Future that can be used with an event loop (Tokio, async_std). The JsRuntime future completes when there is an error or when all pending ops have completed.
Pending ops are created in JavaScript by calling Deno.core.opAsync(), and in Rust by implementing an async function that takes a serde::Deserialize “control argument” and an optional zero copy buffer, each async Op is tied to a Promise in JavaScript.
Implementations
Only constructor, configuration is done through options
.
Ensures core.js has the latest op-name to op-id mappings
Returns the runtime’s op state, which can be used to maintain ops and access resources between op calls.
Executes traditional JavaScript code (traditional = not ES modules).
The execution takes place on the current global context, so it is possible to maintain local JS state and invoke this method multiple times.
name
can be a filepath or any other string, eg.
- “/some/file/path.js”
- “
” - “[native code]”
The same name
value can be used for multiple executions.
AnyError
can be downcast to a type that exposes additional information
about the V8 exception. By default this type is JsError
, however it may
be a different type if RuntimeOptions::js_error_create_fn
has been set.
Takes a snapshot. The isolate should have been created with will_snapshot set to true.
AnyError
can be downcast to a type that exposes additional information
about the V8 exception. By default this type is JsError
, however it may
be a different type if RuntimeOptions::js_error_create_fn
has been set.
Registers an op that can be called from JavaScript.
The op mechanism allows to expose Rust functions to the JS runtime,
which can be called using the provided name
.
This function provides byte-level bindings. To pass data via JSON, the
following functions can be passed as an argument for op_fn
:
Registers a callback on the isolate when the memory limits are approached. Use this to prevent V8 from crashing the process when reaching the limit.
Calls the closure with the current heap limit and the initial heap limit. The return value of the closure is set as the new limit.
Waits for the given value to resolve while polling the event loop.
This future resolves when either the value is resolved or the event loop runs to completion.
Runs event loop to completion
This future resolves when:
- there are no more pending dynamic imports
- there are no more pending ops
- there are no more active inspector sessions (only if
wait_for_inspector
is set to true)
Evaluates an already instantiated ES module.
Returns a receiver handle that resolves when module promise resolves.
Implementors must manually call run_event_loop()
to drive module
evaluation future.
AnyError
can be downcast to a type that exposes additional information
about the V8 exception. By default this type is JsError
, however it may
be a different type if RuntimeOptions::js_error_create_fn
has been set.
This function panics if module has not been instantiated.
pub async fn load_main_module(
&mut self,
specifier: &ModuleSpecifier,
code: Option<String>
) -> Result<ModuleId, AnyError>
pub async fn load_main_module(
&mut self,
specifier: &ModuleSpecifier,
code: Option<String>
) -> Result<ModuleId, AnyError>
Asynchronously load specified module and all of its dependencies.
The module will be marked as “main”, and because of that “import.meta.main” will return true when checked inside that module.
User must call JsRuntime::mod_evaluate
with returned ModuleId
manually after load is finished.
pub async fn load_side_module(
&mut self,
specifier: &ModuleSpecifier,
code: Option<String>
) -> Result<ModuleId, AnyError>
pub async fn load_side_module(
&mut self,
specifier: &ModuleSpecifier,
code: Option<String>
) -> Result<ModuleId, AnyError>
Asynchronously load specified ES module and all of its dependencies.
This method is meant to be used when loading some utility code that might be later imported by the main module (ie. an entry point module).
User must call JsRuntime::mod_evaluate
with returned ModuleId
manually after load is finished.
pub async fn load_module(
&mut self,
specifier: &ModuleSpecifier,
code: Option<String>
) -> Result<ModuleId, AnyError>
👎 Deprecated since 0.100.0: This method had a bug, marking multiple modules loaded as “main”. Use load_main_module
or load_side_module
instead.
pub async fn load_module(
&mut self,
specifier: &ModuleSpecifier,
code: Option<String>
) -> Result<ModuleId, AnyError>
This method had a bug, marking multiple modules loaded as “main”. Use load_main_module
or load_side_module
instead.
Asynchronously load specified module and all of its dependencies
User must call JsRuntime::mod_evaluate
with returned ModuleId
manually after load is finished.