improve polyfill of stable sort

Author: zloirock

packages/core-js/internals/array-sort.js

@@ -4,6 +4,10 @@ var toObject = require('../internals/to-object');
 var toLength = require('../internals/to-length');
 var fails = require('../internals/fails');
 var arrayMethodIsStrict = require('../internals/array-method-is-strict');
+var FF = require('../internals/engine-ff-version');
+var IE_OR_EDGE = require('../internals/engine-is-ie-or-edge');
+var V8 = require('../internals/engine-v8-version');
+var WEBKIT = require('../internals/engine-webkit-version');
 
 var test = [];
 var nativeSort = test.sort;
@@ -21,6 +25,12 @@ var FAILS_ON_NULL = fails(function () {
 var STRICT_METHOD = arrayMethodIsStrict('sort');
 
 var STABLE_SORT = !fails(function () {
+  // feature detection can be too slow, so check engines versions
+  if (V8) return V8 < 70;
+  if (FF && FF > 3) return;
+  if (IE_OR_EDGE) return true;
+  if (WEBKIT) return WEBKIT < 603;
+
   var result = '';
   var code, chr, value, index;
 
@@ -53,14 +63,28 @@ var FORCED = FAILS_ON_UNDEFINED || !FAILS_ON_NULL || !STRICT_METHOD || !STABLE_S
 var mergeSort = function (array, comparefn) {
   var length = array.length;
   var middle = floor(length / 2);
-  if (length < 2) return array;
-  return merge(
+  return length < 8 ? insertionSort(array, comparefn) : merge(
     mergeSort(array.slice(0, middle), comparefn),
     mergeSort(array.slice(middle), comparefn),
     comparefn
   );
 };
 
+var insertionSort = function (array, comparefn) {
+  var length = array.length;
+  var i = 1;
+  var element, j;
+
+  while (i < length) {
+    j = i;
+    element = array[i];
+    while (j && sortCompare(array[j - 1], element, comparefn) > 0) {
+      array[j] = array[--j];
+    }
+    if (j !== i++) array[j] = element;
+  } return array;
+};
+
 var merge = function (left, right, comparefn) {
   var llength = left.length;
   var rlength = right.length;
@@ -78,9 +102,8 @@ var merge = function (left, right, comparefn) {
 };
 
 var sortCompare = function (x, y, comparefn) {
-  if (x === undefined && y === undefined) return 0;
-  if (x === undefined) return 1;
   if (y === undefined) return -1;
+  if (x === undefined) return 1;
   if (comparefn !== undefined) {
     return +comparefn(x, y) || 0;
   } return String(x) > String(y) ? 1 : -1;
@@ -103,6 +126,7 @@ module.exports = FORCED ? function sort(comparefn) {
     if (index in array) items.push(array[index]);
   }
 
+  // TODO: use something more complex like timsort?
   items = mergeSort(items, comparefn);
   itemsLength = items.length;
   index = 0;

packages/core-js/internals/engine-ff-version.js

@@ -0,0 +1,5 @@
+var userAgent = require('../internals/engine-user-agent');
+
+var firefox = userAgent.match(/firefox\/(\d+)/i);
+
+module.exports = !!firefox && +firefox[1];

packages/core-js/internals/engine-is-ie-or-edge.js

@@ -0,0 +1,3 @@
+var UA = require('../internals/engine-user-agent');
+
+module.exports = /MSIE|Trident/.test(UA);

packages/core-js/internals/engine-webkit-version.js

@@ -0,0 +1,5 @@
+var userAgent = require('../internals/engine-user-agent');
+
+var webkit = userAgent.match(/AppleWebKit\/(\d+)\./);
+
+module.exports = !!webkit && +webkit[1];

packages/core-js/internals/object-prototype-accessors-forced.js

@@ -2,14 +2,13 @@
 var IS_PURE = require('../internals/is-pure');
 var global = require('../internals/global');
 var fails = require('../internals/fails');
-var userAgent = require('../internals/engine-user-agent');
+var WEBKIT = require('../internals/engine-webkit-version');
 
 // Forced replacement object prototype accessors methods
 module.exports = IS_PURE || !fails(function () {
   // This feature detection crashes old WebKit
   // https://github.com/zloirock/core-js/issues/232
-  var webkit = userAgent.match(/AppleWebKit\/(\d+)\./);
-  if (webkit && +webkit[1] < 535) return;
+  if (WEBKIT && WEBKIT < 535) return;
   var key = Math.random();
   // In FF throws only define methods
   // eslint-disable-next-line no-undef, no-useless-call -- required for testing

packages/core-js/modules/es.typed-array.sort.js

@@ -2,11 +2,21 @@
 var ArrayBufferViewCore = require('../internals/array-buffer-view-core');
 var fails = require('../internals/fails');
 var $sort = require('../internals/array-sort');
+var FF = require('../internals/engine-ff-version');
+var IE_OR_EDGE = require('../internals/engine-is-ie-or-edge');
+var V8 = require('../internals/engine-v8-version');
+var WEBKIT = require('../internals/engine-webkit-version');
 
 var aTypedArray = ArrayBufferViewCore.aTypedArray;
 var exportTypedArrayMethod = ArrayBufferViewCore.exportTypedArrayMethod;
 
 var STABLE_SORT = !fails(function () {
+  // feature detection can be too slow, so check engines versions
+  if (V8) return V8 < 73;
+  if (FF) return FF < 67;
+  if (IE_OR_EDGE) return true;
+  if (WEBKIT) return WEBKIT < 602;
+
   // eslint-disable-next-line es/no-typed-arrays -- required for testing
   var array = new Uint16Array(516);
   var expected = Array(516);