How to solve this tricky issue?

How to solve this tricky issue?

I'm trying to develop a program to automatically open the "east" region of EasyUI framework by clicking a button. My solution is to change the value of the "collapsed" attribute in the data-options attribute. Take below script for reference: 

<div id="east" data-options="region:'east',split:true,collapsed:true,title:'East'"             style="width:300px;padding:10px;">
</div>

I've used various JQuery ways to do this, but all failed. Below are some of my testing results (with comments)

alert($("#east").attr("data-options")); //the value of data-options can be shown correctly, so it works. 

$("#east").attr("data-options","region:'east',split:true,collapsed:true,title:'East1'");//this line does not work, it is unable to change any attribute values in the data-options attribute.

$("#east").panel({
title: "title123", //this can change the value of the title, so this line works.
collapsed: false, //the status of "collapsed" remains unchanged, so it does not work.
}); 

var panel = $("#mydiv").layout("panel","east"); 
panel.panel({title:"tital"}); //the status of title can be changed, so this line works.
panel.panel({collapsed:true}); // this line does not work.

Could anyone help to change the status of the "collapsed" status, so that i can open the east region automatically? Thanks a lot.