sav

+/**
+ *  Module: sticky
+ *  Desc: 滚动固定
+ *  @author: xuan.chen@yoho.cn
+ */
+
+'use strict';
+
+var Sticky = function(elem, options) {
+    this.options = $.extend({}, Sticky.DEAFAULT, options);
+    this.$elem = $(elem);
+    this.$holder = $('<div></div>').height(this.$elem.height());
+    this.$target = $(this.options.target)
+        .on('scroll.yoho.sticky', $.proxy(this.checkPosition, this));
+
+    this.$elem.wrapper(this.$holder);
+
+    this.checkPosition();
+};
+
+Sticky.DEAFAULT = {
+    top: 0,     // offset top, 距离附着元素的位移
+    target: window  // 附着元素
+};
+
+Sticky.prototype.checkPosition = function() {
+    if (!this.$elem.is('::visible')) {
+        return;
+    }
+};
+
+
+
+module.exports = Sticky;