From db483df9a64a364a273806ec9fc370a473408b92 Mon Sep 17 00:00:00 2001
From: Benjamin Tan <demoneaux@gmail.com>
Date: Mon, 14 Jul 2014 15:37:07 +0800
Subject: [PATCH] Fix issue with cloning typed arrays

Closes #624
---
 lodash.js | 62 ++++++++++++++++++++++++++++++++++++-------------------
 1 file changed, 41 insertions(+), 21 deletions(-)

diff --git a/lodash.js b/lodash.js
index 68f7569c1..2ae86117d 100644
--- a/lodash.js
+++ b/lodash.js
@@ -1427,7 +1427,8 @@
               if (Ctor instanceof Ctor) {
                 Ctor = ctorByClass[className];
               }
-              return new Ctor(cloneBuffer(value.buffer));
+
+              return new Ctor(sliceBuffer(value.buffer, value.byteOffset, value.length * Ctor.BYTES_PER_ELEMENT));
 
             case numberClass:
             case stringClass:
@@ -2903,26 +2904,7 @@
      * @returns {ArrayBuffer} Returns the cloned array buffer.
      */
     function cloneBuffer(buffer) {
-      return bufferSlice.call(buffer, 0);
-    }
-    if (!bufferSlice) {
-      // PhantomJS has `ArrayBuffer` and `Uint8Array` but not `Float64Array`
-      cloneBuffer = !(ArrayBuffer && Uint8Array) ? identity : function(buffer) {
-        var byteLength = buffer.byteLength,
-            floatLength = Float64Array ? floor(byteLength / FLOAT64_BYTES_PER_ELEMENT) : 0,
-            offset = floatLength * FLOAT64_BYTES_PER_ELEMENT,
-            result = new ArrayBuffer(byteLength);
-
-        if (floatLength) {
-          var view = new Float64Array(result, 0, floatLength);
-          view.set(new Float64Array(buffer, 0, floatLength));
-        }
-        if (byteLength != offset) {
-          view = new Uint8Array(result, offset);
-          view.set(new Uint8Array(buffer, offset));
-        }
-        return result;
-      };
+      return sliceBuffer(buffer, 0);
     }
 
     /**
@@ -3011,6 +2993,44 @@
       return result;
     }
 
+    /**
+     * Slices the given array buffer from the `start` index up to, but not including, the `end` index.
+     *
+     * @private
+     * @param {ArrayBuffer} buffer The array buffer to slice.
+     * @param {number} [start=0] The start index.
+     * @param {number} [end=buffer.byteLength] The end index.
+     * @returns {ArrayBuffer} Returns the slice of `buffer`.
+     */
+    function sliceBuffer(buffer, start, end) {
+      typeof start == 'number' || (start = 0);
+      typeof end == 'number' || (end = buffer.byteLength);
+      return bufferSlice.call(buffer, start, end);
+    }
+    if (!bufferSlice) {
+      // PhantomJS has `ArrayBuffer` and `Uint8Array` but not `Float64Array`
+      sliceBuffer = !(ArrayBuffer && Uint8Array) ? identity : function(buffer, start, end) {
+        typeof start == 'number' || (start = 0);
+        typeof end == 'number' || (end = buffer.byteLength);
+
+        var byteLength = end - start,
+            floatLength = Float64Array ? floor(byteLength / FLOAT64_BYTES_PER_ELEMENT) : 0,
+            offset = floatLength * FLOAT64_BYTES_PER_ELEMENT,
+            result = new ArrayBuffer(byteLength);
+
+        if (floatLength) {
+          var view = new Float64Array(result, 0, floatLength);
+          view.set(new Float64Array(buffer, start, floatLength));
+        }
+        if (byteLength != offset) {
+          offset += start;
+          view = new Uint8Array(result, offset);
+          view.set(new Uint8Array(buffer, offset));
+        }
+        return result;
+      };
+    }
+
     /**
      * An implementation of `_.uniq` optimized for sorted arrays without support
      * for callback shorthands and `this` binding.