代码 （直接粘贴进去即可使用）：
防抖节流需要补课的可以点击这里
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Document</title>
<style>
html {
height: 100%;
}
body {
background: #f0f3ef;
height: 100%;
}
.container {
height: 100%;
display: flex;
justify-content: center;
align-items: center;
flex-direction: column;
}
.bgDiv {
box-sizing: border-box;
width: 595px;
height: 55px;
position: relative;
/* position: absolute;
left: 50%;
top: 50%;
transform: translate(-50%, -50%); */
}
.search-input-text {
border: 1px solid #b6b6b6;
width: 495px;
background: #fff;
height: 33px;
line-height: 33px;
font-size: 18px;
padding: 3px 0 0 7px;
}
.search-input-button {
width: 90px;
height: 38px;
color: #fff;
font-size: 16px;
letter-spacing: 3px;
background: #3385ff;
border: 0.5px solid #2d78f4;
margin-left: -5px;
vertical-align: top;
opacity: 0.9;
}
.search-input-button:hover {
opacity: 1;
box-shadow: 0 1px 1px #333;
cursor: pointer;
}
.suggest {
width: 502px;
position: absolute;
top: 38px;
border: 1px solid #999;
background: #fff;
display: none;
}
.suggest ul {
list-style: none;
margin: 0;
padding: 0;
}
.suggest ul li {
padding: 3px;
font-size: 17px;
line-height: 25px;
cursor: pointer;
}
.suggest ul li:hover {
background-color: #e5e5e5;
}
</style>
</head>
<body>
<div class="container">
<div class="bgDiv">
//搜索框
<input
type="text"
class="search-input-text"
value=""
autofocus
placeholder="关键词"
/>
//搜索按钮
<input
type="button"
value="搜索一下"
class="search-input-button"
id="btn"
/>
//搜索建议
<div class="suggest">
<ul id="search-result"></ul>
</div>
</div>
</div>
<script>
var suggestContainer = document.getElementsByClassName("suggest")[0];
var searchInput = document.getElementsByClassName("search-input-text")[0];
var bgDiv = document.getElementsByClassName("bgDiv")[0];
var searchResult = document.getElementById("search-result");
// 清除建议框内容，不是设置css样式，而是实打实的移除节点
function clearContent() {
var size = searchResult.childNodes.length;
for (var i = size - 1; i >= 0; i--) {
searchResult.removeChild(searchResult.childNodes[i]);
}
}
//节流阀
var timer = null;
// 注册输入框键盘抬起事件
searchInput.onkeyup = function (e) {
suggestContainer.style.display = "block";
// 如果输入框内容为空 清除内容且无需跨域请求
if (this.value.length === 0) {
clearContent();
return;
}
if (this.timer) {
clearTimeout(this.timer);
}
if (e.keyCode !== 40 && e.keyCode !== 38) {
// 函数节流优化
this.timer = setTimeout(() => {
// 创建script标签JSONP跨域
var script = document.createElement("script");
script.src =
"https://www.baidu.com/su?&wd=" +
encodeURI(this.value.trim()) +
"&p=3&cb=handleSuggestion";
document.body.appendChild(script);
}, 1300);
}
};
// 回调函数处理返回值
function handleSuggestion(res) {
// 清空之前的数据！！
clearContent();
var result = res.s;
// 截取前五个搜索建议项
if (result.length > 4) {
result = result.slice(0, 5);
}
for (let i = 0; i < result.length; i++) {
// 动态创建li标签
var liObj = document.createElement("li");
liObj.innerHTML = result[i];
searchResult.appendChild(liObj);
}
// 自执行匿名函数--删除用于跨域的script标签
(function () {
var s = document.querySelectorAll("script");
for (var i = 1, len = s.length; i < len; i++) {
document.body.removeChild(s[i]);
}
})();
}
function jumpPage() {
window.open(
`https://www.baidu.com/s?word=${encodeURI(searchInput.value)}`
);
}
// 事件委托 点击li标签或者点击搜索按钮跳转到百度搜索页面
bgDiv.addEventListener(
"click",
function (e) {
if (e.target.nodeName.toLowerCase() === "li") {
var keywords = e.target.innerText;
searchInput.value = keywords;
jumpPage();
} else if (e.target.id === "btn") {
jumpPage();
}
},
false
);
var i = 0;
var flag = 1;
// 事件委托 监听键盘事件
bgDiv.addEventListener(
"keydown",
function (e) {
var size = searchResult.childNodes.length;
if (e.keyCode === 13) {
jumpPage();
}
// 键盘向下事件
if (e.keyCode === 40) {
if (flag === 0) {
i = i + 2;
}
flag = 1;
e.preventDefault();
if (i >= size) {
i = 0;
}
if (i < size) {
searchInput.value = searchResult.childNodes[i++].innerText;
}
}
// 键盘向上事件
if (e.keyCode === 38) {
if (flag === 1) {
i = i - 2;
}
flag = 0;
e.preventDefault();
if (i < 0) {
i = size - 1;
}
if (i > -1) {
searchInput.value = searchResult.childNodes[i--].innerText;
}
}
},
false
);
// 点击页面任何其他地方 搜索结果框消失
document.onclick = () => clearContent();
</script>
</body>
</html>
