JS实现搜索框文字可删除功能

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>JS实现搜索框文字可删除</title>
<style>
*:focus {outline: none; }
body {width: 400px;margin: 100px auto;}
#topsearch {height: 33px;}
#topsearch .input {border: 1px solid #77c03a;height: 100%;}
#topsearch .input .clear {width: 30px;height: 35px;line-height: 30px;text-align: center;padding-right: 10px;visibility: hidden;opacity: 0.8;color: gray;}
#topsearch input[type=text] {height:20px;width: 250px;border: none;padding: 5px;}
#topsearch div {float: left;}
#topsearch button {width: 100px;height: 35px;background: #77c03a;color: #fff;border: none;}
</style>
</head>
<body>
<div id="topsearch">
<div class="input"><input type="text" id="search"><span class="clear" id="delete">×</span></div>
<button type="button" name="searchz">Search</button>
</div>
<script>
document.getElementById("search").addEventListener("keyup", function() {
if (this.value.length > 0) {
document.getElementById("delete").style.visibility = "visible";
document.getElementById("delete").onclick = function() {
document.getElementById("search").value = "";
}
} else {
document.getElementById("delete").style.visibility = "hidden";
}
});
</script>
</body>
</html>