var btn = document.getElementById("btn"); var result = document.getElementById("result"); btn.onclick = function(){ var ary = [0,1,2]; ary[10] = 10; result.innerHTML = ary.filter(function(x) { return x === undefined}); }
<p>点击查看结果:</p> <button id="btn">查看结果</button> <p>结果:</p> <div id="result"></div>
p { font-size: 14px; height 24px; line-height: 24px; }