onkeydown和onkeyup事件不適用於Internet Explorer 8

Question

我的代碼在IE9/IE10，FF，Chrome和Opera上運行時沒有問題，但是在舊版Internet Explorer上運行否鍵盤輸入已處理。

我有以下用於處理事件的代碼。它應該只在按下新按鈕時觸發。

lastEvent = void 0; 

heldKeys = {}; 

window.onkeydown = function(event) { 
if (lastEvent && lastEvent.keyCode === event.keyCode) { 
    return; 
} 
lastEvent = event; 
heldKeys[event.keyCode] = true; 
switch (event.which) { 
    case 80: 
    return myamp.userInput("positiv"); 
    case 81: 
    return myamp.userInput("negativ"); 
} 
}; 

window.onkeyup = function(event) { 
    lastEvent = null; 
    return delete heldKeys[event.keyCode]; 
}; 

Answer 1

嘗試

lastEvent = void 0; 

heldKeys = {}; 

window.onkeydown = function(event) { 
    event = event || window.event; //IE does not pass the event object 
    if (lastEvent && lastEvent.keyCode === event.keyCode) { 
     return; 
    } 
    lastEvent = event; 
    heldKeys[event.keyCode] = true; 

    var keyCode = event.which || event.keyCode; //key property also different 

    switch (keyCode) { 
     case 80: 
      return myamp.userInput("positiv"); 
     case 81: 
      return myamp.userInput("negativ"); 
    } 
}; 

window.onkeyup = function(event) { 
    event = event || window.event; 
    lastEvent = null; 
    return delete heldKeys[event.keyCode]; 
}; 

Answer 2

您必須使用規範化的密鑰代碼。像這樣：

var keyCode = event.which || event.keyCode; 

Answer 3

您需要綁定到文檔而不是窗口。

window.onkeyup = function(event) { 
window.onkeydown = function(event) { 

必須

document.onkeyup = function(event) { 
document.onkeydown = function(event) { 

Answer 4

我想盡了各種辦法，但這些仍然沒有在IE8中正常工作。我想出了這個工作是這樣的：

window.onkeyup = function(e) { 
    e = (e) ? e : window.event; // check if e is defined 
    var kc = (e) ? e.which : e.keyCode; // assign keyCode 
    key = (key === undefined) ? e.keyCode : kc; // if keyCode still undefined, reassign it 
    if (kc == 13) { 
     //enter was pressed 
    } 
    // other code 
}