緩存event.target有意義嗎？

Question

考慮到JavaScript代碼，緩存event.target是否有優勢？我使用這種事件來避免千名事件調解員加入競爭者。

要我這樣做：

$element.addEventListener("click",function(event) 
{ 

    if(event.target.id == "someid") 
    { 
     event.target.dosomething 
     event.target.dosomething 
     event.target.dosomething 
     event.target.dosomething 
    } 
    else if (event.target.id == "someanotherid") 
    { 
     event.target.dosomething 
     event.target.dosomething 
     event.target.dosomething 
     event.target.dosomething 
    } 

}); 

或本：

$element.addEventListener("click",function(event) 
    { 

     if(event.target.id == "someid") 
     { 
      var targetA = event.target; 

      targetA.dosomething 
      targetA.dosomething 
      targetA.dosomething 
      targetA.dosomething 
     } 
     else if (event.target.id == "someanotherid") 
     { 
      var targetB = event.target; 

      targetB.dosomething 
      targetB.dosomething 
      targetB.dosomething 
      targetB.dosomething 
     } 

    }); 

Answer 1

是的，這有一定道理。變量比屬性查找更快。不，你應該這樣做

$element.addEventListener("click", function(event) { 
    var target = event.target; 
    if (target.id == "someid") { 
     target.dosomething1 
     target.dosomething2 
     target.dosomething3 
     target.dosomething4 
    } else if (target.id == "someanotherid") { 
     target.dosomethingelse1 
     target.dosomethingelse2 
     target.dosomethingelse3 
     target.dosomethingelse4 
    } 
});