Vue监听事件

一、问题场景

项目有个需求，在登录页面，输入好账号密码后，直接可以点击回车就能够登录，效果和点击登录按钮一样，登录页面源码如下

查看网上教程，需要绑定一个键盘事件

keyup(键盘事件)是按键松开，当指定的按键松开会触发的事件

@keyup.enter="keyDown(e)

keydown() 是在键盘按下就会触发，传入一个e(键盘事件对象，有一个属性是keycode)

在登录按钮那里我加上了这个点击事件，如下，添加了一个按键事件

    登录

把函数写出来(在methods中）

// 点击回车键登录
    keyDown(e) {
      // 回车则执行登录方法 enter键的ASCII是13
      if (e.keyCode == 13) {
        this.login(); // 定义的登录方法
      }

运行项目，打开页面，输入账号密码，按回车

 根本监听不到任何键盘事件

二、问题解决

在生命周期mounted或created里面加入监听键盘事件，通过判断keyCode来确定按键类型，注意和methods同级

为什么要这样？这个涉及到Vue的生命周期，就是Vue实例在创建时候会经历不同的阶段，每个阶段对应一系列的生命周期钩子函数，会自动调用这些函数

created是组件实例被创建后立即调用的钩子函数

mounted是组件实例被挂载到DOM后调用的钩子函数

在组件被创立或者被挂载后，绑定监听键盘按键的函数，让其自动调用，就可以监听键盘事件了

mounted() {
    // 绑定监听事件
    window.addEventListener("keydown", this.keyDown);
  },

最后记得关闭窗口监听，在destroyed函数(也是生命周期钩子函数，意为vue实例销毁后)中，释放资源

destroyed() {
    // 销毁事件
    window.removeEventListener("keydown", this.keyDown, false);
  },

完整的页面代码如下

效果，输入账号密码后，按下回车，登录成功，页面跳转

三、总结

Vue生命周期需要好好学，可以参见我的这篇笔记

Vue生命周期_Bugman.的博客-CSDN博客

最后附上一张keycode对照表

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