实现Tab键的空格功能

有时使用编辑框需要用到按Tab键空两格，可能这时Tab键的功能不是空格而是页面切换等，这时需要设置：

　　　　$(document).bind('keydown', function (event) {
            if (event.keyCode == 9) {
                return false;
            }
        });

event.keycode值大全 ：

1 keycode 8 = BackSpace BackSpace

2 keycode 9 = Tab Tab

3 keycode 12 = Clear

4 keycode 13 = Enter

5 keycode 16 = Shift_L

6 keycode 17 = Control_L

7 keycode 18 = Alt_L

8 keycode 19 = Pause

9 keycode 20 = Caps_Lock

10 keycode 27 = Escape Escape

11 keycode 32 = space space

12 keycode 33 = Prior

13 keycode 34 = Next

14 keycode 35 = End

15 keycode 36 = Home

16 keycode 37 = Left

17 keycode 38 = Up

18 keycode 39 = Right

19 keycode 40 = Down

20 keycode 41 = Select

21 keycode 42 = Print

22 keycode 43 = Execute

23 keycode 45 = Insert

24 keycode 46 = Delete

25 keycode 47 = Help

26 keycode 48 = 0 equal braceright

27 keycode 49 = 1 exclam onesuperior

28 keycode 50 = 2 quotedbl twosuperior

29 keycode 51 = 3 section threesuperior

30 keycode 52 = 4 dollar

31 keycode 53 = 5 percent

32 keycode 54 = 6 ampersand

33 keycode 55 = 7 slash braceleft

34 keycode 56 = 8 parenleft bracketleft

35 keycode 57 = 9 parenright bracketright

36 keycode 65 = a A

37 keycode 66 = b B

38 keycode 67 = c C

39 keycode 68 = d D

40 keycode 69 = e E EuroSign

41 keycode 70 = f F

......