e.which沒有工作在IE 9

Question

我使用下面的代碼從JavaScript

var whichCode = (window.event) ? e.which : e.keyCode; 

但是得到鍵碼值，它做工精細，除了IE 9，它返回未定義在E 。哪一個。

Answer 1

此代碼在哪裏執行？請添加完整的代碼。你應該在事件處理程序中使用它！ 假設是正確放置試試這個

var keycodeValue = e.which || e.keyCode; 

其中E是事件收到

Answer 2

KeyboardEvent.which從未在Internet Explorer中得到實施，被認爲是其他的棄用。

的MDN說明how to most correctly handle keyboard events：

window.addEventListener("keydown", function (event) { 
    if (event.defaultPrevented) { 
    return; // Should do nothing if the default action has been cancelled 
    } 

    var handled = false; 
    if (event.key !== undefined) { 
    // Handle the event with KeyboardEvent.key and set handled true. 
    } else if (event.keyIdentifier !== undefined) { 
    // Handle the event with KeyboardEvent.keyIdentifier and set handled true. 
    } else if (event.keyCode !== undefined) { 
    // Handle the event with KeyboardEvent.keyCode and set handled true. 
    } 

    if (handled) { 
    // Suppress "double action" if event handled 
    event.preventDefault(); 
    } 
}, true); 

現在，假設你沒有處理keyDown事件，你也可以使用

var whichCode = e.charCode !== undefined ? e.charCode : e.keyCode; 

注意，這是exactly how it is done in jQuery瀏覽器兼容性：

if (event.which == null) { 
    event.which = original.charCode != null ? original.charCode : original.keyCode; 
}