问题
I am new to Sencha ExtJs
I did not understand the line Ext.getCmp('component_id').getEl().hide();. what is the use of .getEl(). Can i write Ext.getCmp('component_id').hide(); directly?
And explain me about .el, Ext.get() also.
回答1:
Ext.getCmp() VS Ext.get()
Ext.getCmp() finds an existing (created) component in ExtJS component tree. Note that it is discouraged to use it. Rely on ComponentQuery instead.
Ext.get() finds a DOM element by id. For example:
<html>
<body>
<div id="target">Hello, world!</div>
</body>
</html>
Ext.get('target') will return div#target DOM element.
I personally never use either one. Instead, I locate components using ComponentQuery and then retrieve their DOM elements, as described below.
MyCmp.getEl() VS MyCmp.el
Both just retrieve the top level DOM element of the MyCmp component.
Current version of ExtJS (4.2.1) defines the .getEl() function as follows:
MyCmp.getEl = function () {
return this.el;
}
Which means that MyCmp.getEl() and MyCmp.el are absolutely equal.
Use .el if you prefer to keep your code short and sweet. However, .getEl() might be useful in case if in the future ExtJS adds additional logic to the component's DOM element retrieval process (e.g. checking whether it exists or not first).
I prefer .el.
MyCmp.hide() VS MyCmp.el.hide()
MyCmp.hide() and MyCmp.el.hide() are two different functions. Current version of ExtJS (4.2.1) defines them as follows:
MyCmp.hide = function (animateTarget, cb, scope) {
var me = this,
continueHide;
if (me.pendingShow) {
delete me.pendingShow;
} if (!(me.rendered && !me.isVisible())) {
continueHide = (me.fireEvent('beforehide', me) !== false);
if (me.hierarchicallyHidden || continueHide) {
me.hidden = true;
me.getHierarchyState().hidden = true;
if (me.rendered) {
me.onHide.apply(me, arguments);
}
}
}
return me;
}
and
MyCmp.el.hide = function (animate){
if (typeof animate == 'string'){
this.setVisible(false, animate);
return this;
}
this.setVisible(false, this.anim(animate));
return this;
}
However, both functions seem to produce identical results. They just add a style="display: none;" to the component's DOM element.
I use MyCmp.hide().
回答2:
1)
Ext.getCmp('')-> ExtJS maintains component list when page is constructed. Using getCmp('unique ID') fetches component from the list2)
getEl()-> returns HTML element / DOM of the component3)
hide()-> just applies css (e.g.:"display:none") to the style of the component
So
Ext.getCmp('component_id').hide()
is equivalent to
Ext.getCmp('component_id').getEl().hide()
来源：https://stackoverflow.com/questions/16166017/can-you-please-explain-el-getel-ext-get-in-detail