如何設置一個鍵來改變節點的風格？

Question

我正在做一個Greasemonkey的用戶腳本，我想要設置一個按鍵來將的樣式display:""更改爲block，反之亦然按一個鍵（本例中爲「Home」）。

var bluebar = document.getElementById('pagelet_bluebar'); 
bluebar.style.display = "none"; 
document.addEventListener("keydown", function (e) { 
    if (e.keyCode == 36) { 
     showhideui(); 
    } 
}, false); 
function showhideui() { 
    if (bluebar.style.display = "none") { 
     bluebar.style.display = "block"; 
    } else if (bluebar.style.display = "block") { 
     bluebar.style.display = "none"; 
    } 
} 

的解決方案是增加而不是==在=的條件：

if (bluebar.style.display == "none") 
else if (bluebar.style.display == "block") 

Answer 1

使用==或===，而不是在您的比較單一=跡象。
檢查此鏈接瞭解comparison operators

var bluebar = document.getElementById('pagelet_bluebar'); 
    document.addEventListener("keydown", function (e) { 
     if (e.keyCode === 36) { //press "Home" key change to block/none 
      showhideui(); 
     } 
    }, false); 
    function showhideui() { 
     if (bluebar.style.display == "none") { //if is none 
      bluebar.style.display = "block" ; //change to block 
     } else if (bluebar.style.display == "block" || bluebar.style.display == "") { //if is block 
      bluebar.style.display = "none"; //change to none 
     } 
    } 

PS：如果只有這兩個可能性，你甚至可以用更綜合的方式：

(bluebar.style.display == "block" || bluebar.style.display == "") ? bluebar.style.display = "none" : bluebar.style.display = "block";