Add shortOut helper.

lodash.js

@@ -1494,6 +1494,7 @@
         nativeKeys = overArg(Object.keys, Object),
         nativeMax = Math.max,
         nativeMin = Math.min,
+        nativeNow = Date.now,
         nativeParseInt = context.parseInt,
         nativeRandom = Math.random,
         nativeReverse = arrayProto.reverse;
@@ -3873,7 +3874,7 @@
     }
 
     /**
-     * The base implementation of `setData` without support for hot loop detection.
+     * The base implementation of `setData` without support for hot loop shorting.
      *
      * @private
      * @param {Function} func The function to associate metadata with.
@@ -3885,6 +3886,23 @@
       return func;
     };
 
+    /**
+     * The base implementation of `setToString` without support for hot loop shorting.
+     *
+     * @private
+     * @param {Function} func The function to modify.
+     * @param {Function} string The `toString` result.
+     * @returns {Function} Returns `func`.
+     */
+    var baseSetToString = !nativeDefineProperty ? identity : function(func, string) {
+      return nativeDefineProperty(func, 'toString', {
+        'configurable': true,
+        'enumerable': false,
+        'value': constant(string),
+        'writable': true
+      });
+    };
+
     /**
      * The base implementation of `_.slice` without an iteratee call guard.
      *
@@ -6368,25 +6386,7 @@
      * @param {*} data The metadata.
      * @returns {Function} Returns `func`.
      */
-    var setData = (function() {
-      var count = 0,
-          lastCalled = 0;
-
-      return function(key, value) {
-        var stamp = now(),
-            remaining = HOT_SPAN - (stamp - lastCalled);
-
-        lastCalled = stamp;
-        if (remaining > 0) {
-          if (++count >= HOT_COUNT) {
-            return key;
-          }
-        } else {
-          count = 0;
-        }
-        return baseSetData(key, value);
-      };
-    }());
+    var setData = shortOut(baseSetData);
 
     /**
      * A simple wrapper around the global [`setTimeout`](https://mdn.io/setTimeout).
@@ -6408,14 +6408,7 @@
      * @param {Function} string The `toString` result.
      * @returns {Function} Returns `func`.
      */
-    var setToString = !nativeDefineProperty ? identity : function(func, string) {
-      return nativeDefineProperty(func, 'toString', {
-        'configurable': true,
-        'enumerable': false,
-        'value': constant(string),
-        'writable': true
-      });
-    };
+    var setToString = shortOut(baseSetToString);
 
     /**
      * Sets the `toString` method of `wrapper` to mimic the source of `reference`
@@ -6432,6 +6425,35 @@
       return setToString(wrapper, insertWrapDetails(source, updateWrapDetails(getWrapDetails(source), bitmask)));
     }
 
+    /**
+     * Creates a function that'll short out and invoke `identity` instead
+     * of `func` when it's called `HOT_COUNT` or more times in `HOT_SPAN`
+     * milliseconds.
+     *
+     * @private
+     * @param {Function} func The function to restrict.
+     * @returns {Function} Returns the new shortable function.
+     */
+    function shortOut(func) {
+      var count = 0,
+          lastCalled = 0;
+
+      return function() {
+        var stamp = nativeNow(),
+            remaining = HOT_SPAN - (stamp - lastCalled);
+
+        lastCalled = stamp;
+        if (remaining > 0) {
+          if (++count >= HOT_COUNT) {
+            return arguments[0];
+          }
+        } else {
+          count = 0;
+        }
+        return func.apply(undefined, arguments);
+      };
+    }
+
     /**
      * Converts `string` to a property path array.
      *