键盘event.which属性

IE中，只有keyCode属性，而FireFox中有which和charCode属性

event.which属性对DOM原生的event.keyCode和event.charCode进行了标准化。

function keypress(e){
    e = e || window.event;
    var currKey = e.which || e.charCode || e.keyCode;var keyName = String.fromCharCode(currKey);
    console.log("按键码: " + currKey + " 字符: " + keyName);
}

document.onkeypress = function(e){
    keypress(e);
}