diff --git a/js/src/jsnum.cpp b/js/src/jsnum.cpp
index b778c8d739..573b55cc85 100644
--- a/js/src/jsnum.cpp
+++ b/js/src/jsnum.cpp
@@ -1768,6 +1768,35 @@ js::ToIntegerIndex(JSContext* cx, JS::HandleValue v, uint64_t* index)
     return true;
 }
 
+// ES2017 draft 7.1.17 ToIndex
+bool
+js::ToIndex(JSContext* cx, JS::HandleValue v, uint64_t* index)
+{
+    // Step 1.
+    if (v.isUndefined()) {
+        *index = 0;
+        return true;
+    }
+
+    // Step 2.a.
+    double integerIndex;
+    if (!ToInteger(cx, v, &integerIndex))
+        return false;
+
+    // Inlined version of ToLength.
+    // 1. Already an integer.
+    // 2. Step eliminates < 0, +0 == -0 with SameValueZero.
+    // 3/4. Limit to <= 2^53-1, so everything above should fail.
+    if (integerIndex < 0 || integerIndex >= DOUBLE_INTEGRAL_PRECISION_LIMIT) {
+        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_BAD_INDEX);
+        return false;
+    }
+
+    // Step 3.
+    *index = uint64_t(integerIndex);
+    return true;
+}
+
 template <typename CharT>
 bool
 js_strtod(ExclusiveContext* cx, const CharT* begin, const CharT* end, const CharT** dEnd,
diff --git a/js/src/jsnum.h b/js/src/jsnum.h
index 9866a91eeb..bd53fdc1a0 100644
--- a/js/src/jsnum.h
+++ b/js/src/jsnum.h
@@ -308,6 +308,15 @@ MOZ_MUST_USE bool ToLengthClamped(T* cx, HandleValue v, uint32_t* out, bool* ove
  */
 MOZ_MUST_USE bool ToIntegerIndex(JSContext* cx, JS::HandleValue v, uint64_t* index);
 
+/* ES2017 draft 7.1.17 ToIndex
+ *
+ * Return true and set |*index| to the integer value if |v| is a valid
+ * integer index value. Otherwise report a RangeError and return false.
+ *
+ * The returned index will always be in the range 0 <= *index <= 2^53-1.
+ */
+MOZ_MUST_USE bool ToIndex(JSContext* cx, JS::HandleValue v, uint64_t* index);
+
 MOZ_MUST_USE inline bool
 SafeAdd(int32_t one, int32_t two, int32_t* res)
 {
diff --git a/js/src/vm/ArrayBufferObject.cpp b/js/src/vm/ArrayBufferObject.cpp
index 5d355ada9d..3bed40af47 100644
--- a/js/src/vm/ArrayBufferObject.cpp
+++ b/js/src/vm/ArrayBufferObject.cpp
@@ -264,27 +264,24 @@ ArrayBufferObject::fun_isView(JSContext* cx, unsigned argc, Value* vp)
     return true;
 }
 
-/*
- * new ArrayBuffer(byteLength)
- */
+
+// ES2017 draft 24.1.2.1
 bool
 ArrayBufferObject::class_constructor(JSContext* cx, unsigned argc, Value* vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
 
+    // Step 1.
     if (!ThrowIfNotConstructing(cx, args, "ArrayBuffer"))
         return false;
 
-    int32_t nbytes = 0;
-    if (argc > 0 && !ToInt32(cx, args[0], &nbytes))
+    // Step 2.
+    uint64_t byteLength;
+    if (!ToIndex(cx, args.get(0), &byteLength))
         return false;
 
-    if (nbytes < 0) {
-        /*
-         * We're just not going to support arrays that are bigger than what will fit
-         * as an integer value; if someone actually ever complains (validly), then we
-         * can fix.
-         */
+    // Non-standard: Refuse to allocate buffers larger than ~2 GiB.
+    if (byteLength > INT32_MAX) {
         JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_BAD_ARRAY_LENGTH);
         return false;
     }
@@ -294,7 +291,7 @@ ArrayBufferObject::class_constructor(JSContext* cx, unsigned argc, Value* vp)
     if (!GetPrototypeFromConstructor(cx, newTarget, &proto))
         return false;
 
-    JSObject* bufobj = create(cx, uint32_t(nbytes), proto);
+    JSObject* bufobj = create(cx, uint32_t(byteLength), proto);
     if (!bufobj)
         return false;
     args.rval().setObject(*bufobj);
diff --git a/js/src/vm/TypedArrayObject.cpp b/js/src/vm/TypedArrayObject.cpp
index 0225c0578c..ac93ec9b14 100644
--- a/js/src/vm/TypedArrayObject.cpp
+++ b/js/src/vm/TypedArrayObject.cpp
@@ -1898,10 +1898,8 @@ DataViewObject::class_constructor(JSContext* cx, unsigned argc, Value* vp)
 
 template <typename NativeType>
 /* static */ uint8_t*
-DataViewObject::getDataPointer(JSContext* cx, Handle<DataViewObject*> obj, double offset)
+DataViewObject::getDataPointer(JSContext* cx, Handle<DataViewObject*> obj, uint64_t offset)
 {
-    MOZ_ASSERT(offset >= 0);
-
     const size_t TypeSize = sizeof(NativeType);
     if (offset > UINT32_MAX - TypeSize || offset + TypeSize > obj->byteLength()) {
         JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_ARG_INDEX_OUT_OF_RANGE,
@@ -1989,31 +1987,6 @@ struct DataViewIO
     }
 };
 
-static bool
-ToIndex(JSContext* cx, HandleValue v, double* index)
-{
-    if (v.isUndefined()) {
-        *index = 0.0;
-        return true;
-    }
-
-    double integerIndex;
-    if (!ToInteger(cx, v, &integerIndex))
-        return false;
-
-    // Inlined version of ToLength.
-    // 1. Already an integer
-    // 2. Step eliminates < 0, +0 == -0 with SameValueZero
-    // 3/4. Limit to <= 2^53-1, so everything above should fail.
-    if (integerIndex < 0 || integerIndex > 9007199254740991) {
-        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_BAD_INDEX);
-        return false;
-    }
-
-    *index = integerIndex;
-    return true;
-}
-
 template<typename NativeType>
 /* static */ bool
 DataViewObject::read(JSContext* cx, Handle<DataViewObject*> obj,
@@ -2023,7 +1996,7 @@ DataViewObject::read(JSContext* cx, Handle<DataViewObject*> obj,
     // Step 3. unnecessary assert
 
     // Step 4.
-    double getIndex;
+    uint64_t getIndex;
     if (!ToIndex(cx, args.get(0), &getIndex))
         return false;
 
@@ -2111,7 +2084,7 @@ DataViewObject::write(JSContext* cx, Handle<DataViewObject*> obj,
     // Step 3. unnecessary assert
 
     // Step 4.
-    double getIndex;
+    uint64_t getIndex;
     if (!ToIndex(cx, args.get(0), &getIndex))
         return false;
 
diff --git a/js/src/vm/TypedArrayObject.h b/js/src/vm/TypedArrayObject.h
index ccdee22bee..196d347075 100644
--- a/js/src/vm/TypedArrayObject.h
+++ b/js/src/vm/TypedArrayObject.h
@@ -442,7 +442,7 @@ class DataViewObject : public NativeObject
 
     template <typename NativeType>
     static uint8_t*
-    getDataPointer(JSContext* cx, Handle<DataViewObject*> obj, double offset);
+    getDataPointer(JSContext* cx, Handle<DataViewObject*> obj, uint64_t offset);
 
     template<Value ValueGetter(DataViewObject* view)>
     static bool