$('body').keyup(function(){
    if(event.keyCode==13){
        $('#sub').click();
    }
});

又或者是这样写:

$('body').keyup(function(e){
    if(e.keyCode === 13){
        $('#sub').trigger('click');
    }
});

其中,keyup代表javascript当中松开某键盘按钮这一事件。

keycode对照表

左边是keyCode等号后面的按键代码，右边是代表的键盘对应按钮。

8 => BackSpace
9 => Tab Tab
12 => Clear
13 => 回车
16 => 左Shift
17 => 左Ctrl
18 => 左Alt
19 => Pause
20 => Caps_Lock
27 => Escape Escape
32 => space space
33 => Prior
34 => Next
35 => End
36 => Home
37 => 左
38 => 上
39 => 右
40 => 下
41 => Select
42 => Print
43 => Execute
45 => Insert
46 => Delete
47 => Help
48 => 0 equal braceright
49 => 1 exclam onesuperior
50 => 2 quotedbl twosuperior
51 => 3 section threesuperior
52 => 4 $
53 => 5 %
54 => 6 ampersand
55 => 7 slash braceleft
56 => 8 parenleft bracketleft
57 => 9 parenright bracketright
65 => a A
66 => b B
67 => c C
68 => d D
69 => e E EuroSign
70 => f F
71 => g G
72 => h H
73 => i I
74 => j J
75 => k K
76 => l L
77 => m M mu
78 => n N
79 => o O
80 => p P
81 => q Q at
82 => r R
83 => s S
84 => t T
85 => u U
86 => v V
87 => w W
88 => x X
89 => y Y
90 => z Z
96 => KP_0 KP_0
97 => KP_1 KP_1
98 => KP_2 KP_2
99 => KP_3 KP_3
100 => KP_4 KP_4
101 => KP_5 KP_5
102 => KP_6 KP_6
103 => KP_7 KP_7
104 => KP_8 KP_8
105 => KP_9 KP_9
106 => KP_Multiply KP_Multiply
107 => KP_Add KP_Add
108 => KP_Separator KP_Separator
109 => KP_Subtract KP_Subtract
110 => KP_Decimal KP_Decimal
111 => KP_Divide KP_Divide
112 => F1
113 => F2
114 => F3
115 => F4
116 => F5
117 => F6
118 => F7
119 => F8
120 => F9
121 => F10
122 => F11
123 => F12
124 => F13
125 => F14
126 => F15
127 => F16
128 => F17
129 => F18
130 => F19
131 => F20
132 => F21
133 => F22
134 => F23
135 => F24
136 => Num_Lock
137 => Scroll_Lock
187 => acute grave
188 => comma semicolon
189 => minus underscore
190 => period colon
192 => numbersign apostrophe
210 => plusminus hyphen macron
211 =>
212 => copyright registered
213 => guillemotleft guillemotright
214 => masculine ordfeminine
215 => ae AE
216 => cent yen
217 => questiondown exclamdown
218 => onequarter onehalf threequarters
220 => less greater bar
221 => plus asterisk asciitilde
227 => multiply division
228 => acircumflex Acircumflex
229 => ecircumflex Ecircumflex
230 => icircumflex Icircumflex
231 => ocircumflex Ocircumflex
232 => ucircumflex Ucircumflex
233 => ntilde Ntilde
234 => yacute Yacute
235 => oslash Ooblique
236 => aring Aring
237 => ccedilla Ccedilla
238 => thorn THORN
239 => eth ETH
240 => diaeresis cedilla currency
241 => agrave Agrave atilde Atilde
242 => egrave Egrave
243 => igrave Igrave
244 => ograve Ograve otilde Otilde
245 => ugrave Ugrave
246 => adiaeresis Adiaeresis
247 => ediaeresis Ediaeresis
248 => idiaeresis Idiaeresis
249 => odiaeresis Odiaeresis
250 => udiaeresis Udiaeresis
251 => ssharp question backslash
252 => asciicircum degree
253 => 3 sterling
254 => Mode_switch