convert isArrayBuffer() to generic isInstance() function

diff --git a/index.js b/index.js
index b2f6676521ce7b3edb38dd2a477f88972acca872..4b98dea777007da4c9391d4469525298b41efcd2 100644 (file)
--- a/index.js
+++ b/index.js
@@ -120,7 +120,8 @@ function from (value, encodingOrOffset, length) {
     )
   }
 
-  if (isArrayBuffer(value) || (value && isArrayBuffer(value.buffer))) {
+  if (isInstance(value, ArrayBuffer) ||
+      (value && isInstance(value.buffer, ArrayBuffer))) {
     return fromArrayBuffer(value, encodingOrOffset, length)
   }
 
@@ -383,7 +384,7 @@ function byteLength (string, encoding) {
   if (Buffer.isBuffer(string)) {
     return string.length
   }
-  if (ArrayBuffer.isView(string) || isArrayBuffer(string)) {
+  if (ArrayBuffer.isView(string) || isInstance(string, ArrayBuffer)) {
     return string.byteLength
   }
   if (typeof string !== 'string') {
@@ -1729,12 +1730,12 @@ function blitBuffer (src, dst, offset, length) {
   return i
 }
 
-// ArrayBuffers from another context (i.e. an iframe) do not pass the `instanceof` check
-// but they should be treated as valid. See: https://github.com/feross/buffer/issues/166
-function isArrayBuffer (obj) {
-  return obj instanceof ArrayBuffer ||
-    (obj != null && obj.constructor != null && obj.constructor.name === 'ArrayBuffer' &&
-      typeof obj.byteLength === 'number')
+// ArrayBuffer or Uint8Array objects from other contexts (i.e. iframes) do not pass
+// the `instanceof` check but they should be treated as of that type.
+// See: https://github.com/feross/buffer/issues/166
+function isInstance (obj, type) {
+  return obj instanceof type ||
+    (obj != null && obj.constructor != null && obj.constructor.name === type.name)
 }
 
 function numberIsNaN (obj) {