extjs学习笔记（三）
extjs学习笔记（三）最基本的grid
     extjs的一个亮点就是提供了丰富的UI，使得没有艺术细胞的程序员也能做出绚丽的界面。把所有的UI集中到一起，有好处也有坏处，好处是有了统一的风格和接口，坏处是js文件过于庞大，使用extjs的最小集合也超过了500k，所以在有些项目中并不适用。jquery在这方面则正好相反，它的UI都以插件形式提供，可以需要什么就引用什么，所以非常小巧灵活，但由于插件往往是由不同的人或者团队来提供，界面和接口往往就不那么一致。反正是各有千秋吧。
    今天学习extjs中的grid，它可以说是功能强大，无出其右，只有你想不到的，没有它做不到的，呵呵，好像是有点夸张了。好，不说废话了，我们就从最简单的grid开始，一步步来看看extjs给我们提供的grid究竟给我们提供了哪些功能。
    一个grid包括一些行和列，在extjs里边，列由Ext.grid.ColumnModel来管理，我们来看看如何创建一个ColumnModel对象：

1var cm = new Ext.grid.ColumnModel([
2    {id:'company',header: "Company", width: 160, sortable: true, dataIndex: 'company'},
3    {header: "Price", width: 75, sortable: true,  dataIndex: 'price'},
4    {header: "Change", width: 75, sortable: true,  dataIndex: 'change'},
5    {header: "% Change", width: 75, sortable: true,  dataIndex: 'pctChange'},
6    {header: "Last Updated", width: 85, sortable: true, dataIndex: 'lastChange'}
7]);
    这里定义了五个列,列可以通过参数进行配置：id用来标识列，在css中使用该id可以对整列所有的单元格设置样式，可自动扩充的列也根据这个id来标识；header是列名字；width是列的宽度;sortable用来指明列是否可排序，dataIndex，先不管它。比较常用的参数还有renderer，指示列如何来呈现，后边会再详细介绍它。
    有了列，我们还需要一些数据来填充行，构造一个数组吧：

1var myData = [
2        ['3m Co',71.72,0.02,0.03,'9/1 12:00am'],
3        ['Alcoa Inc',29.01,0.42,1.47,'9/1 12:00am'],
4        ['Altria Group Inc',83.81,0.28,0.34,'9/1 12:00am'],
5        ['American Express Company',52.55,0.01,0.02,'9/1 12:00am'],
6        ['American International Group, Inc.',64.13,0.31,0.49,'9/1 12:00am'],
7        ['AT&T Inc.',31.61,-0.48,-1.54,'9/1 12:00am'],
8        ['Boeing Co.',75.43,0.53,0.71,'9/1 12:00am'],
9        ['Caterpillar Inc.',67.27,0.92,1.39,'9/1 12:00am'],
10        ['Citigroup, Inc.',49.37,0.02,0.04,'9/1 12:00am'],
11        ['E.I. du Pont de Nemours and Company',40.48,0.51,1.28,'9/1 12:00am'],
12        ['Exxon Mobil Corp',68.1,-0.43,-0.64,'9/1 12:00am'],
13        ['General Electric Company',34.14,-0.08,-0.23,'9/1 12:00am'],
14        ['General Motors Corporation',30.27,1.09,3.74,'9/1 12:00am'],
15        ['Hewlett-Packard Co.',36.53,-0.03,-0.08,'9/1 12:00am'],
16        ['Honeywell Intl Inc',38.77,0.05,0.13,'9/1 12:00am'],
17        ['Intel Corporation',19.88,0.31,1.58,'9/1 12:00am'],
18        ['International Business Machines',81.41,0.44,0.54,'9/1 12:00am'],
19        ['Johnson & Johnson',64.72,0.06,0.09,'9/1 12:00am'],
20        ['JP Morgan & Chase & Co',45.73,0.07,0.15,'9/1 12:00am'],
21        ['McDonald\'s Corporation',36.76,0.86,2.40,'9/1 12:00am'],
22        ['Merck & Co., Inc.',40.96,0.41,1.01,'9/1 12:00am'],
23        ['Microsoft Corporation',25.84,0.14,0.54,'9/1 12:00am'],
24        ['Pfizer Inc',27.96,0.4,1.45,'9/1 12:00am'],
25        ['The Coca-Cola Company',45.07,0.26,0.58,'9/1 12:00am'],
26        ['The Home Depot, Inc.',34.64,0.35