每天一个JS 小demo之留言板。主要知识点:DOM方法的理解和运用
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Document</title> <style type="text/css"> .wrap { width: 400px; margin: 30px auto; } textarea { display: block; width: 100%; height: 60px; } input { display: block; width: 60%; margin: 15px auto; } li { padding: 5px 10px; position: relative; word-break: break-all; } .red { color: #000; background: #f1f1f1; } .pink { color: #000; background: #ccc; } a { position: absolute; right: 0; top: -20px; background: yellow; color: #fff; } #list { margin: 0; padding: 0; list-style: none; font: 14px/26px "宋体"; } .clos { position: absolute; top: 0; right: -50px; width: 50px; color: #fff; background: #000; padding: 5px 0; text-decoration: none; text-align: center; } .clos:hover { box-shadow: 0 0 5px rgba(0,0,0,.5) } </style> <script type="text/javascript"> window.onload = function(){ var btn = document.querySelector('input'); var text = document.querySelector('textarea'); var list = document.querySelector('#list'); var colors = ["red","pink"]; var nub = 0; btn.onclick = function(){ if(text.value.trim() == ""){ alert("打点字吧"); return false; } var li = document.createElement("li"); li.innerHTML = text.value; // li.className = colors[nub%colors.length]; /* 判断a标签已经被添加,就让a标签显示出来,否则就添加 */ if(list.children[0]&&list.children[0].className=="red"){ li.className = "pink"; } else { li.className = "red"; } var a = null; li.onmouseover = function(){ if(a) { a.style.display = "block"; } else { a = document.createElement("a"); a.href = "javascript:;"; a.className = "clos"; a.innerHTML = "删除"; a.onclick = function (){ list.removeChild(this.parentNode); }; this.appendChild(a); } }; li.onmouseout = function(){ a.style.display = "none"; }; list.insertBefore(li,list.children[0]); text.value = ""; nub++; }; }; </script> </head> <body> <div> <div class="wrap"> <textarea id="text"></textarea> <input type="button" value="创建元素"> <ul id="list"></ul> </div> </body> </html>
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