ExtJS4.x设立表单中控件为可用

ExtJS4.x设置表单中控件为可用
整体代码如下所示，窗体加载的时候，4个文本框是不可用的，点击保存按钮后获得窗体4个文本框可进行编辑，现在我通过下边这句获得到了窗体中4个文本框控件

var formT = this.up('form').query('textfield');

获得后进行循环，forEach如何能让formT进行单一循环

Ext.Array.forEach(formT, function(field) {

   然后在这里对获得到的那个textfield控件进行可用设置

}

Ext.onReady(function(){

  	        var formPanel;

            formPanel = Ext.widget('form', {

                renderTo: Ext.getBody(),

                title: 'Complete Check Out',

                frame: true,

                width: 550,

                bodyPadding: 5,

                fieldDefaults: {

                    labelAlign: 'right',

                    labelWidth: 90,

                    msgTarget: 'qtip'

                },

                items: [

                    // Billing Address

                    {

                        xtype: 'fieldset',

                        title: 'Billing Address',

                        layout: 'anchor',

                        defaults: {

                            anchor: '100%'

                        },

                        items: [{

                            xtype: 'checkbox',

                            name: 'billingSameAsMailing',

                            boxLabel: 'Same as Mailing Address?',