你能给我看一些键盘映射的例子吗.js，(权威指南）

function Keymap(bindings) {
    this.map = {};    // Define the key identifier->handler map
    if (bindings) {   // Copy initial bindings into it
        for(name in bindings) this.bind(name, bindings[name]);
    }
}
// Bind the specified key identifier to the specified handler function
Keymap.prototype.bind = function(key, func) {
    this.map[Keymap.normalize(key)] = func;
};
// Delete the binding for the specified key identifier
Keymap.prototype.unbind = function(key) {
    delete this.map[Keymap.normalize(key)];
};
// Install this Keymap on the specified HTML element
Keymap.prototype.install = function(element) {
    // This is the event-handler function
    var keymap = this;
    function handler(event) { return keymap.dispatch(event, element); }
    // Now install it
    if (element.addEventListener)
        element.addEventListener("keydown", handler, false);
    else if (element.attachEvent) 
        element.attachEvent("onkeydown", handler);
};
// This method dispatches key events based on the keymap bindings.
Keymap.prototype.dispatch = function(event, element) {
    // We start off with no modifiers and no key name
    var modifiers = ""
    var keyname = null;
    // Build the modifier string in canonical lowercase alphabetical order.
    if (event.altKey) modifiers += "alt_";      
    if (event.ctrlKey) modifiers += "ctrl_";
    if (event.metaKey) modifiers += "meta_";
    if (event.shiftKey) modifiers += "shift_";
    // The keyname is easy if the DOM Level 3 key property is implemented:
    if (event.key) keyname = event.key;
    // Use the keyIdentifier on Safari and Chrome for function key names
    else if (event.keyIdentifier && event.keyIdentifier.substring(0,2) !== "U+")
        keyname = event.keyIdentifier;
    // Otherwise, use the keyCode property and the code-to-name map below
    else keyname = Keymap.keyCodeToKeyName[event.keyCode];
    // If we couldn't figure out a key name, just return and ignore the event.
    if (!keyname) return;
    // The canonical key id is modifiers plus lowercase key name
    var keyid = modifiers + keyname.toLowerCase();
    // Now see if the key identifier is bound to anything
    var handler = this.map[keyid];
    if (handler) {  // If there is a handler for this key, handle it
        // Invoke the handler function
        var retval = handler.call(element, event, keyid);
        // If the handler returns false, cancel default and prevent bubbling
        if (retval === false) {
            if (event.stopPropagation) event.stopPropagation();  // DOM model
            else event.cancelBubble = true;                      // IE model
            if (event.preventDefault) event.preventDefault();    // DOM
            else event.returnValue = false;                      // IE
        }
        // Return whatever the handler returned
        return retval;
    }
};
// Utility function to convert a key identifier to canonical form.
// On non-Macintosh hardware, we could map "meta" to "ctrl" here, so that
// Meta-C would be "Command-C" on the Mac and "Ctrl-C" everywhere else.
Keymap.normalize = function(keyid) {
    keyid = keyid.toLowerCase();           // Everything lowercase
    var words = keyid.split(/'s+|['-+_]/); // Split modifiers from name
    var keyname = words.pop();             // keyname is the last word
    keyname = Keymap.aliases[keyname] || keyname; // Is it an alias?
    words.sort();                          // Sort remaining modifiers
    words.push(keyname);                   // Add the normalized name back 
    return words.join("_");                // Concatenate them all
};
Keymap.aliases = {        // Map common key aliases to their "official" 
    "escape":"esc",       // key names used by DOM Level 3 and by 
    "delete":"del",       // the key code to key name map below.
    "return":"enter",     // Both keys and values must be lowercase here.
    "ctrl":"control",
    "space":"spacebar",
    "ins":"insert"
};
// The legacy keyCode property of the keydown event object is not standardized
// But the following values seem to work for most browsers and OSes.
Keymap.keyCodeToKeyName = {
    // Keys with words or arrows on them
    8:"Backspace", 9:"Tab", 13:"Enter", 16:"Shift", 17:"Control", 18:"Alt",
    19:"Pause", 20:"CapsLock", 27:"Esc", 32:"Spacebar", 33:"PageUp",  
    34:"PageDown", 35:"End", 36:"Home", 37:"Left", 38:"Up", 39:"Right",
    40:"Down", 45:"Insert", 46:"Del",
    // Number keys on main keyboard (not keypad)
    48:"0",49:"1",50:"2",51:"3",52:"4",53:"5",54:"6",55:"7",56:"8",57:"9",
    // Letter keys. Note that we don't distinguish upper and lower case
    65:"A", 66:"B", 67:"C", 68:"D", 69:"E", 70:"F", 71:"G", 72:"H", 73:"I",
    74:"J", 75:"K", 76:"L", 77:"M", 78:"N", 79:"O", 80:"P", 81:"Q", 82:"R",
    83:"S", 84:"T", 85:"U", 86:"V", 87:"W", 88:"X", 89:"Y", 90:"Z",
    // Keypad numbers and punctuation keys. (Opera does not support these.)
    96:"0",97:"1",98:"2",99:"3",100:"4",101:"5",102:"6",103:"7",104:"8",105:"9",
    106:"Multiply", 107:"Add", 109:"Subtract", 110:"Decimal", 111:"Divide",
    // Function keys
    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",
    // Punctuation keys that don't require holding down Shift
    // Hyphen is nonportable: FF returns same code as Subtract
    59:";", 61:"=", 186:";", 187:"=", // Firefox and Opera return 59,61 
    188:",", 190:".", 191:"/", 192:"`", 219:"[", 220:"''", 221:"]", 222:"'"
};

JavaScript：权威指南：第 6 个键盘映射.js

键映射.js：将键事件绑定到处理程序函数。

此模块定义一个键盘映射类。此类的实例表示 键标识符(定义如下(到处理程序函数的映射。键盘映射 可以安装在 HTML 元素上以处理键关闭事件。当这样的 发生事件时，键盘映射使用其映射来调用相应的处理程序。

创建键盘映射时，可以传递一个 JavaScript 对象，该对象表示 键盘映射的初始绑定集。此对象的属性名称 是键标识器，属性值是处理程序函数。 创建键映射后，可以通过传递键来添加新绑定 bind(( 方法的标识符和处理程序函数。您可以删除 通过将密钥标识符传递给 unbind(( 方法进行绑定。

要使用键盘映射，请调用其 install(( 方法，传递一个 HTML 元素， 例如文档对象。install(( 将一个 onkeydown 事件处理程序添加到 指定的对象。调用此处理程序时，它将确定键 按下的键的标识符并调用处理程序函数(如果有(， 绑定到该密钥标识符。单个键盘映射可以安装在多个 一个 HTML 元素。

密钥标识符

标识符是键加号的不区分大小写的字符串表示形式 同时按住的任何修饰键。键名称为 通常是键上的(未移动的(文本。法定键名称包括"A"、"7"、 "F2"、"PageUp"、"Left"、"Backspace"和"Esc"。

有关名称列表，请参阅此模块中的 Keymap.keyCodeToKeyName 对象。 这些是由 DOM 级别 3 标准定义的名称的子集，并且 此类在实现时将使用事件对象的键属性。

密钥标识符还可以包括修饰符键前缀。这些前缀是 Alt、Ctrl、Meta 和 Shift。它们不区分大小写，必须分开 从键名以及带有空格或下划线的彼此之间， 连字符或 +。例如："SHIFT+A"、"Alt_F2"、"meta-v"和"ctrl alt left"。 在 Mac 上，Meta 是 Command 键，Alt 是 Option 键。一些浏览器 将 Windows 键映射到元修饰符。

处理程序函数

处理程序作为文档或文档元素的方法调用，其 键盘映射已安装并传递两个参数： 1( 键控事件的事件对象 2( 按下的键的键标识符 处理程序返回值将成为键向下处理程序的返回值。 如果处理程序函数返回 false，则键盘映射将停止冒泡并 取消与键关闭事件关联的任何默认操作。

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