diff --git a/src/compatibility/array/indexOf.js b/src/compatibility/array/indexOf.js
new file mode 100644
index 0000000..98c1cb3
--- /dev/null
+++ b/src/compatibility/array/indexOf.js
@@ -0,0 +1,21 @@
+if (!Array.prototype.indexOf) {
+  Array.prototype.indexOf = function (element , start) {
+    var start = start ? start : 0, length;
+    if (!this) {
+      throw new TypeError();
+    }
+    length = this.length;
+    if (length === 0 || start >= length) {
+      return -1;
+    }
+    if (start < 0) {
+      start = length - Math.abs(start);
+    }
+    for (var i = start; i < length; i++) {
+      if (this[i] === element) {
+        return i;
+      }
+    }
+    return -1;
+  };
+}
\ No newline at end of file
diff --git a/src/compatibility/document/querySelectorAll.js b/src/compatibility/document/querySelectorAll.js
new file mode 100644
index 0000000..4fbbee9
--- /dev/null
+++ b/src/compatibility/document/querySelectorAll.js
@@ -0,0 +1,12 @@
+if (!document.querySelectorAll && document.createStyleSheet) {
+  document.querySelectorAll = function (selector) {
+    var all = document.all, result = [], style = document.createStyleSheet();
+    style.addRule(selector, 'fake:fake');
+    for (var i = all.length - 1; i >= 0; i--) {
+      if (all[i].currentStyle.fake === 'fake') {
+        result.push(all[i]);
+      }
+    }
+    style.removeRule(0); return result;
+  }
+}
\ No newline at end of file
diff --git a/src/echo.js b/src/echo.js
index e7e1f75..4e89920 100644
--- a/src/echo.js
+++ b/src/echo.js
@@ -1,16 +1,3 @@
-if (!document.querySelectorAll && document.createStyleSheet) {
-  document.querySelectorAll = function (selector) {
-    var all = document.all, result = [], style = document.createStyleSheet();
-    style.addRule(selector, 'fake:fake');
-    for (var i = all.length - 1; i >= 0; i--) {
-      if (all[i].currentStyle.fake === 'fake') {
-        result.push(all[i]);
-      }
-    }
-    style.removeRule(0); return result;
-  }
-}
-
 window.Echo = (function (window, document, undefined) {
 
   'use strict';
@@ -28,8 +15,8 @@ window.Echo = (function (window, document, undefined) {
       var self = store[i];
       if (_inView(self)) {
         self.src = self.getAttribute('data-echo');
-        if ([].indexOf && [].slice.call(store).indexOf(self) !== -1) {
-          [].slice.call(store).splice(i, 1);
+        if (store.indexOf(self) !== -1) {
+          store.splice(i, 1);
         }
       }
     }