[oden-js] ArrayBuffer values

oden-js/src/value.rs

@@ -323,6 +323,20 @@ impl ValueRef {
             ))
         }
     }
+
+    /// Get the underlying bytes for a an ArrayBuffer object. Obviously it
+    /// only works if this is an un-detached ArrayBuffer value.
+    pub fn get_array_buffer<'a>(&'a self, ctx: &ContextRef) -> Result<&'a [u8]> {
+        unsafe {
+            let mut size: usize = 0;
+            let buffer = sys::JS_GetArrayBuffer(ctx.ctx, &mut size as *mut usize, self.val);
+            if buffer.is_null() {
+                Err(ctx.exception_error())
+            } else {
+                Ok(std::slice::from_raw_parts(buffer, size))
+            }
+        }
+    }
 }
 
 impl fmt::Debug for ValueRef {