Factor out createSizePropertyCheck (#2694)

Author: jgonggrijp

modules/index.js

@@ -156,24 +156,26 @@ function deepGet(obj, path) {
   return length ? obj : void 0;
 }
 
+// Common logic for isArrayLike and isBufferLike.
+var MAX_ARRAY_INDEX = Math.pow(2, 53) - 1;
+function createSizePropertyCheck(getSizeProperty) {
+  return function(collection) {
+    var sizeProperty = getSizeProperty(collection);
+    return typeof sizeProperty == 'number' && sizeProperty >= 0 && sizeProperty <= MAX_ARRAY_INDEX;
+  }
+}
+
 // Helper for collection methods to determine whether a collection
 // should be iterated as an array or as an object.
 // Related: https://people.mozilla.org/~jorendorff/es6-draft.html#sec-tolength
 // Avoids a very nasty iOS 8 JIT bug on ARM-64. #2094
-var MAX_ARRAY_INDEX = Math.pow(2, 53) - 1;
 var getLength = shallowProperty('length');
-function isArrayLike(collection) {
-  var length = getLength(collection);
-  return typeof length == 'number' && length >= 0 && length <= MAX_ARRAY_INDEX;
-}
+var isArrayLike = createSizePropertyCheck(getLength);
 
 // Likewise to determine whether we should spend extensive checks against
 // `ArrayBuffer` et al.
 var getByteLength = shallowProperty('byteLength');
-function isBufferLike(collection) {
-  var byteLength = getByteLength(collection);
-  return typeof byteLength == 'number' && byteLength >= 0 && byteLength <= MAX_ARRAY_INDEX;
-}
+var isBufferLike = createSizePropertyCheck(getByteLength);
 
 // Collection Functions
 // --------------------