diff --git a/package.json b/package.json
index c76266c..fed6e53 100644
--- a/package.json
+++ b/package.json
@@ -19,4 +19,4 @@
   "lint-staged": {
     "*.{js,css,md}": "prettier --write"
   }
-}
+}
\ No newline at end of file
diff --git a/src/index.js b/src/index.js
index e1f14d3..8ac2870 100644
--- a/src/index.js
+++ b/src/index.js
@@ -85,24 +85,24 @@ function trigger(target, key, type, newValue) {
    */
   const effectsToRun = new Set();
   effects &&
-    effects.forEach((effect) => {
-      effectsToRun.add(effect);
+    effects.forEach((effectFn) => {
+      effectsToRun.add(effectFn);
     });
 
   // for ... in 循环时， 因为增加和删除都会影响对象的长度和 for 循环的次数，要重新执行一遍副作用函数
   if (type === triggerType.ADD || type === triggerType.DELETE) {
     iterateEffects &&
-      iterateEffects.forEach((effect) => {
-        effectsToRun.add(effect);
+      iterateEffects.forEach((effectFn) => {
+        effectsToRun.add(effectFn);
       });
   }
   // 当类型是 triggerType.add 时， 并且是数组时，将函数加入到effectsToRun中运行
   if (type === triggerType.ADD && Array.isArray(target)) {
     const lengthEffects = depsMap.get("length");
     lengthEffects &&
-      lengthEffects.forEach((effect) => {
-        if (effect !== activeEffect) {
-          effectsToRun.add(effect);
+      lengthEffects.forEach((effectFn) => {
+        if (effectFn !== activeEffect) {
+          effectsToRun.add(effectFn);
         }
       });
   }
@@ -187,7 +187,8 @@ function createReactive(obj, isShallow = false, isReadonly = false) {
       }
 
       // 只读属性不触发收集依赖
-      if (!isReadonly) {
+      // 或者 property 属性类型不是 symbol 值时，不触发依赖 ( for ... of 遍历时 property属性是 symbol [@@Symbol.iterator])
+      if (!isReadonly && typeof p !== "symbol") {
         track(target, p);
       }
 
@@ -210,7 +211,9 @@ function createReactive(obj, isShallow = false, isReadonly = false) {
     },
     // 拦截 for ... in 的响应式变量
     ownKeys(target) {
-      track(target, ITERATE_KEY);
+      // for ... in 遍历时。检测对象是否是数组，如果是数组,使用 length 属性建立连接
+      // 否则 ITERATE_KEY 属性建立连接
+      track(target, Array.isArray(target) ? "length" : "ITERATE_KEY");
       return Reflect.ownKeys(target);
     },
     // 拦截 delete 操作符
diff --git a/src/index.spec.js b/src/index.spec.js
index ec687fe..7077117 100644
--- a/src/index.spec.js
+++ b/src/index.spec.js
@@ -199,14 +199,26 @@ import { computed, effect, reactive, readonly, shallowReactive, shallowReadonly,
 
 /**
  * todo: 代理数组
- * 数组索引与 length :
+ * 数组索引与 length
+ * 数组遍历
  */
 
-// 数组索引与 length
-const arr = reactive(["foo"]);
+// // 数组索引与 length
+// const arr = reactive(["foo"]);
+// effect(() => {
+//   console.log(arr[0]);
+// });
+//
+// arr[0] = "bar";
+// arr.length = 0;
+
+// for ... in 数组遍历
+const arr = reactive([1, 2, 3]);
 effect(() => {
-  console.log(arr.length);
+  for (const res in arr) {
+    console.log(res);
+  }
 });
 
-arr[2] = "bar";
+// arr[3] = "bar";
 arr.length = 0;
diff --git a/src/note.excalidraw b/src/note.excalidraw
index 0461c4f..f0a9ad6 100644
--- a/src/note.excalidraw
+++ b/src/note.excalidraw
@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:4fb121fb92b120d76b6f54a160c6d0d4c081b84bdccf227effa74bb63c71f181
-size 1611979
+oid sha256:3d9dd37a9ce8c102b487bbd3e3e4ac15cebdd275037dd585cce920e71c8fe6ad
+size 1656068