在用Extjs进行网页开发的时候，遇见了一下两个错误，这两个错误的位置用firebug调试显示在extjs-all.js 

Ext.resetElement is undefined

g.el is null

其实这与extjs-all.js完全无关，因为有时候你在js代码里少打了个","号，extjs认不出来，也会显示错误在extjs-all.js

那么这两个错误怎么解决呢？

经过用Google搜索，终于在Stackoverflow，得到了一个正确答案。

Make sure you are using Ext.onReady(function() { ... }). ExtJS uses Ext.resetElementwhich is set before onReady call.

也就是在把extjs代码写在Ext.onReady(function() { ...extjs代码.. })；里。

问题果然解决了。

?
Ext.onReady(function(){
Ext.create('Ext.form.Panel', {
    title: '选择',
    bodyPadding: 5,
    width: 280,
 
    // The form will submit an AJAX request to this URL when submitted
   // url: 'save-form.php',
 
    // Fields will be arranged vertically, stretched to full width
    layout: 'anchor',
    defaults: {
        anchor: '100%'
    },
 
    // The fields
    defaultType: 'textfield',
    items: [{
        fieldLabel: '车次号',
        name: 'trainno',
        allowBlank: false
    },{
         
     //xtype: 'datepicker',
     xtype: 'datefield',
        anchor: '100%',
        fieldLabel: '日期',
        name: 'to_date',
        value: new Date(),  // defaults to today
     maxDate: new Date(),
     handler: function(picker, date) {
         // do something with the selected date
     }
    }
    ],
 
    // Reset and Submit buttons
    buttons: [{
        text: '重置',
        handler: function() {
            this.up('form').getForm().reset();
        }
    }, {
        text: '确认',
        formBind: true, //only enabled once the form is valid
        disabled: true,
        handler: function() {
            var form = this.up('form').getForm();
            if (form.isValid()) {
                form.submit({
                    success: function(form, action) {
                       Ext.Msg.alert('Success', action.result.msg);
                    },
                    failure: function(form, action) {
                        Ext.Msg.alert('Failed', action.result.msg);
                    }
                });
            }
        }
    }],
    renderTo:"left"
});
});

比如上面这个代码我如果不加Ext.onReady(function() { ...extjs代码.. })；里就会报g.el is null错误，导致面板无法正常显示。