Merge pull request #4 from ClayWangT/ClayWangT-patch-1

[fix] sandbox reducer behavior

Author: DeAntiWang

src/sandbox.js

@@ -70,25 +70,32 @@ export function wrapProtoMethod(executor) {
   };
 
   Array.prototype.reduce = function reduce(reducer, init) {
+    const hasInit = arguments.length > 1;
     if (typeof reducer === 'function' && funcToString.call(reducer).indexOf(FUNC_MARK) !== -1) {
-      return executor((function* (array) {
-        let result = init;
-        for (let i = 0; i < array.length; i++) result = yield reducer(result, array[i], i, array);
+      return executor(function* (array) {
+        let result = hasInit ? init : array[0];
+        for (let i = hasInit ? 0 : 1; i < array.length; i++) result = yield reducer(result, array[i], i, array);
         return result;
-      })(this));
+      }(this));
     }
-    return oriArrayReduce.call(this, reducer, init);
+    if (hasInit) return oriArrayReduce.call(this, reducer, init);
+    return oriArrayReduce.call(this, reducer);
   };
 
   Array.prototype.reduceRight = function reduceRight(reducer, init) {
+    const hasInit = arguments.length > 1;
     if (typeof reducer === 'function' && funcToString.call(reducer).indexOf(FUNC_MARK) !== -1) {
-      return executor((function* (array) {
-        let result = init;
-        for (let i = array.length - 1; i !== -1; i--) result = yield reducer(result, array[i], i, array);
+      return executor(function* (array) {
+        let result = hasInit? init : array[array.length - 1];;
+
+        for (let i = hasInit ? array.length - 1: array.length - 2; i !== -1; i--) result = yield reducer(result, array[i], i, array);
+
         return result;
-      })(this));
+      }(this));
     }
-    return oriArrayReduceRight.call(this, reducer, init);
+
+    if(hasInit) return oriArrayReduceRight.call(this, reducer, init);
+    return oriArrayReduceRight.call(this, reducer);
   };
 
   Array.prototype.every = function every(predicate, thisArg) {