About Extjs method of obtaining container and elements

1, the parent of the current object (the object superior)

this.ownerCt: 

2, the current object is a next adjacent objects

this.nextSibling(); 

3, currently on a neighboring target object

this.previousSibling(); 

4, the first child of the current container

this.get(0); （这个好像在Ext6.0不能用了，我用着不好使）
this.items.first(); 

5, the current object is the last child of container

this.items.last(); 

6, find the current object of all higher-level match of the container

this.findParentByType(String xtype) 

7, find the current object matching all subordinate components

this.findByType(String xtype)

8, the upward-match lookup component

this.up("xtype")  

9, down to find matching components

this.down("xtype")   

10, any component matching (common)

Ext.ComponemtQuery("#id")
Ext.ComponemtQuery("xtype")
Ext.ComponemtQuery("xtype[title="..."]")