fix(napi): wrong string length

napi/src/js_values/string.rs

@@ -1,31 +1,24 @@
-use std::convert::{TryFrom, TryInto};
+use std::convert::TryFrom;
 use std::mem;
-use std::os::raw::c_char;
 use std::ptr;
 use std::slice;
 use std::str;
 
 use super::Value;
 use crate::error::check_status;
-use crate::{sys, Error, JsNumber, Result, Status};
+use crate::{sys, Error, Result, Status};
 
 #[derive(Clone, Copy, Debug)]
 pub struct JsString(pub(crate) Value);
 
 impl JsString {
+  #[inline]
   pub fn len(&self) -> Result<usize> {
-    let mut raw_length = ptr::null_mut();
-    unsafe {
-      let status = sys::napi_get_named_property(
-        self.0.env,
-        self.0.value,
-        "length\0".as_ptr() as *const c_char,
-        &mut raw_length,
-      );
-      check_status(status)?;
-    }
-    let length: JsNumber = JsNumber::from_raw_unchecked(self.0.env, raw_length);
-    length.try_into()
+    let mut length = 0;
+    check_status(unsafe {
+      sys::napi_get_value_string_utf8(self.0.env, self.0.value, ptr::null_mut(), 0, &mut length)
+    })?;
+    Ok(length as usize)
   }
 }
 

test_module/__test__/string.spec.js

@@ -0,0 +1,8 @@
+const test = require('ava')
+
+const bindings = require('../index.node')
+
+test('should be able to concat string', (t) => {
+  const fixture = 'JavaScript 🌳 你好 napi'
+  t.snapshot(bindings.concatString(fixture))
+})

test_module/__test__/string.spec.js.md

@@ -0,0 +1,11 @@
+# Snapshot report for `test_module/__test__/string.spec.js`
+
+The actual snapshot is saved in `string.spec.js.snap`.
+
+Generated by [AVA](https://avajs.dev).
+
+## should be able to concat string
+
+> Snapshot 1
+
+    'JavaScript 🌳 你好 napi + Rust 🦀 string!'

test_module/src/lib.rs

@@ -20,6 +20,7 @@ mod either;
 mod external;
 mod function;
 mod napi_version;
+mod string;
 mod symbol;
 mod task;
 
@@ -58,6 +59,7 @@ fn init(module: &mut Module) -> Result<()> {
   module.create_named_method("eitherNumberString", either_number_string)?;
   module.create_named_method("dynamicArgumentLength", dynamic_argument_length)?;
   module.create_named_method("createTestClass", class::create_test_class)?;
+  module.create_named_method("concatString", string::concat_string)?;
   #[cfg(napi4)]
   module.create_named_method("testExecuteTokioReadfile", test_execute_tokio_readfile)?;
   #[cfg(napi4)]

test_module/src/string.rs

@@ -0,0 +1,8 @@
+use napi::{CallContext, JsString, Result};
+
+#[js_function(1)]
+pub fn concat_string(ctx: CallContext) -> Result<JsString> {
+  let in_string = ctx.get::<JsString>(0)?;
+  let out_string = format!("{} + Rust 🦀 string!", in_string.as_str()?);
+  ctx.env.create_string_from_std(out_string)
+}