Struct JsStringLatin1 

pub struct JsStringLatin1<'env> { /* private fields */ }

Implementations

impl<'env> JsStringLatin1<'env>

pub fn from_data(env: &'env Env, data: Vec<u8>) -> Result<JsStringLatin1<'env>>

Try to create a new JavaScript latin1 string from a Rust Vec<u8> without copying the data

Behavior

The copied parameter in the underlying node_api_create_external_string_latin1 call indicates whether the string data was copied into V8’s heap rather than being used as an external reference.

When copied is true:

• String data is copied to V8’s heap
• Finalizer is called immediately if provided
• Original buffer can be freed after the call
• Performance benefit of external strings is not achieved

When copied is false:

• V8 creates an external string that references the original buffer without copying
• Original buffer must remain valid for the lifetime of the JS string
• Finalizer called when string is garbage collected
• Memory usage and copying overhead is reduced

Common scenarios where copied is true:

• String is too short (typically < 10-15 characters)
• V8 heap is under memory pressure
• V8 is running with pointer compression or sandbox features
• Invalid Latin-1 encoding that requires sanitization
• Platform doesn’t support external strings
• Memory alignment issues with the provided buffer

The copied parameter serves as feedback to understand whether the external string optimization was successful or if V8 fell back to traditional string creation.

pub unsafe fn from_external<T: 'env, F: FnOnce(Env, T) + 'env>( env: &'env Env, data: *const u8, len: usize, finalize_hint: T, finalize_callback: F, ) -> Result<JsStringLatin1<'env>>

Creates an external Latin-1 string from raw data with a custom finalize callback.

Safety

The caller must ensure that:

• The data pointer is valid for the lifetime of the string
• The finalize callback properly cleans up the data

Behavior

The copied parameter in the underlying node_api_create_external_string_latin1 call indicates whether the string data was copied into V8’s heap rather than being used as an external reference.

When copied is true:

• String data is copied to V8’s heap
• Finalizer is called immediately if provided
• Original buffer can be freed after the call
• Performance benefit of external strings is not achieved

When copied is false:

• V8 creates an external string that references the original buffer without copying
• Original buffer must remain valid for the lifetime of the JS string
• Finalizer called when string is garbage collected
• Memory usage and copying overhead is reduced

Common scenarios where copied is true:

• String is too short (typically < 10-15 characters)
• V8 heap is under memory pressure
• V8 is running with pointer compression or sandbox features
• Invalid Latin-1 encoding that requires sanitization
• Platform doesn’t support external strings
• Memory alignment issues with the provided buffer

The copied parameter serves as feedback to understand whether the external string optimization was successful or if V8 fell back to traditional string creation.

pub fn from_static( env: &'env Env, string: &'static str, ) -> Result<JsStringLatin1<'env>>

pub fn as_slice(&self) -> &[u8]

pub fn len(&self) -> usize

pub fn is_empty(&self) -> bool

pub fn take(self) -> Vec<u8>

pub fn into_value(self) -> JsString<'env>

pub fn into_latin1_string(self) -> Result<String>

Trait Implementations

impl From<JsStringLatin1<'_>> for Vec<u8>

fn from(value: JsStringLatin1<'_>) -> Self

Converts to this type from the input type.

impl ToNapiValue for JsStringLatin1<'_>

unsafe fn to_napi_value( _: napi_env, val: JsStringLatin1<'_>, ) -> Result<napi_value>

Safety

fn into_unknown(self, env: &Env) -> Result<Unknown<'_>>