自己嘗試著寫了一個計算器，span 為 div的子元素，給div綁定了click事件，但點擊span時瀏覽器報錯，無法實現(xiàn)預期效果。html：<div class = "container col-sm-offset-5">           <div class="row " id = "display-sec">             <div class="col-sm-4" style="background-color:black">               <span id = "distxt">0</span>             </div>           </div>           <div class="row">             <div class="col-sm-1  calButton ">               <span class="calValue" id="ac">AC</span>             </div>             <div class="col-sm-1 calButton " >               <span class="calValue" id="negative">+/-</span>             </div>             <div class="col-sm-1 calButton " >               <span class="calValue" id="percent">%</span>             </div>             <div class="col-sm-1 calButton  lastcol" >               <span class="calValue" id="divide">/</span>             </div>         </div>javascript click事件綁定：當點擊span時無法觸發(fā),div綁定事件。PS:小白不想用JQ，謝謝！