---
tags: API,DOM,第一章
---
# 串接API之DOM第一章
# 基礎知識
JavaScript的組成
1.ECMAscript:JavaScript語法
2.DOM:頁面文檔對象模型
3.BOM:瀏覽器對象模型
Web APIs
1.是W3C組織的標準
2.學習DOM和BOM
3.JS獨有
API和WebAPI
1.API是提供一個接口，幫我們實現某種功能，不必糾結內部如何實現
2.WebAPI做瀏覽器交互效果
3.WebAPI有輸入和輸出，很多都是方法(函數)
4.WebAPI當成學內置對象
# DOM
Document Object Model
文檔對象模型
W3C推薦的處理可擴展標記語言(HTML或XML)
標準編程接口
# 獲取頁面元素
1.根據ID
2.根據標籤名
3.根據HTML5新增方法
4.特殊元素
## document.getElementById
https://developer.mozilla.org/zh-CN/docs/Web/API/Document/getElementById
```
<body>
<div id="time">2100-1-1</div>
<script>
var timer = document.getElementById('time');
console.log(timer); // 返回一个匹配到 ID 的 DOM Element 对象
console.log(typeof timer);
console.dir(timer); // 返回元素對象，只是更好查看裡面的屬性和方法
</script>
</body>
```
## document.getElementsByTagName
```html=
<body>
<ul>
<li>天線寶寶說你好</li>
<li>天線寶寶說你好</li>
<li>天線寶寶說你好</li>
<li>天線寶寶說你好</li>
<li>天線寶寶說你好</li>
</ul>
<ol id="ol">
<li>乒乒乓乓</li>
<li>乒乒乓乓</li>
<li>乒乒乓乓</li>
<li>乒乒乓乓</li>
<li>乒乒乓乓</li>
</ol>
<script>
var lis = document.getElementsByTagName('li');
console.log(lis); // 偽數組
console.log(lis[0]);
for (var i = 0; i < lis.length; i++) {
console.log(lis[i]);
}
// 只有一個li還是返回偽數組
// 沒有li返回空的偽數組
// var ol = document.getElementsByTagName('ol');
// console.log(ol[0].getElementsByTagName('li')); // 父元素必須是指定的單個元素
var ol = document.getElementById('ol');
console.log(ol.getElementsByTagName('li'));
</script>
</body>
```
## querySelector
H5新增方法
```html=
<body>
<div class="box">盒子1</div>
<div class="box">盒子2</div>
<div id="nav">
<ul>
<li>首頁</li>
<li>產品</li>
</ul>
</div>
<script>
// 根據類名獲得某些元素集合
var boxs = document.getElementsByClassName('box');
console.log(boxs);
// 返回指定選擇器的第一個元素對象
var firstBox = document.querySelector('.box');
console.log(firstBox);
var nav = document.querySelector('#nav');
console.log(nav);
var li = document.querySelector('li');
console.log(li);
// 返回指定選擇器的所有元素對象
var allBox = document.querySelectorAll('.box');
console.log(allBox);
</script>
</body>
```
## 獲取body獲取html
```
<body>
<script>
// 獲取body
var bodyEle = document.body;
console.log(bodyEle);
console.dir(bodyEle);
// 獲取html
var htmlEle = document.html;
console.log(htmlEle); // 不行
var htmlEle = document.documentElement;
console.log(htmlEle);
</script>
</body>
```
# 事件
事件三要素
1.事件源
事件觸發對象
EX:按鈕
2.事件類型
如何觸發
EX:滑鼠點擊、滑鼠經過、鍵盤按下
3.事件處理程序
利用函數賦值
```
<body>
<button id="btn">唐伯虎</button>
<script>
var btn = document.getElementById('btn');
btn.onclick = function () {
alert('點秋香');
};
</script>
</body>
```
| 鼠標事件 | 觸發條件 |
| ----------- | ---------------- |
| onclick | 滑鼠點擊左鍵觸發 |
| onmouseover | 滑鼠經過觸發 |
| onmouseout | 滑鼠離開觸發 |
| onfocus | 獲得滑鼠焦點觸發 |
| onblur | 失去滑鼠焦點觸發 |
| onmousemove | 滑鼠移動觸發 |
| onmouseup | 滑鼠彈起觸發 |
| onmousedown | 滑鼠按下觸發 |
## 操作元素
```
<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>
div {
width: 300px;
height: 30px;
line-height: 30px;
color: #fff;
background-color: pink;
}
</style>
</head>
<body>
<button>顯示系統時間</button>
<div>某個時間</div>
<p>123</p>
<script>
// 1.獲取元素
var btn = document.querySelector('button');
var div = document.querySelector('div');
// 2.註冊事件
btn.onclick = function () {
div.innerText = getDate();
};
function getDate() {
var date = new Date();
var year = date.getFullYear();
var month = date.getMonth() + 1;
var dates = date.getDate();
var arr = [
'星期日',
'星期一',
'星期二',
'星期三',
'星期四',
'星期五',
'星期六'
];
var day = date.getDay();
return (
'今天是:' + year + '年' + month + '月' + dates + '日 ' + arr[day]
);
}
var p = document.querySelector('p');
p.innerText = getDate();
</script>
</body>
```
## innerText innerHTML
```
<body>
<div></div>
<p>
安安你好
<span>123</span>
</p>
<script>
// 1.innerText 不識別html標籤 非標準
var div = document.querySelector('div');
div.innerText = '<strong>今天是</strong>晴天';
// 2.innerHTML 識別html標籤 W3C標準 保留空格和換行
div.innerHTML = '<strong>今天是</strong>晴天';
var p = document.querySelector('p');
console.log(p.innerText);
console.log(p.innerHTML);
</script>
</body>
```
## 修改元素屬性
1 innerText innerHTML
2 src href
3 id alt title
```
<body>
<button id="komame">茸茸鼠</button>
<button id="stanley">史丹利</button>
<br>
<img src="komame.jpg" alt="" title="茸茸鼠" />
<script>
var mouse = document.getElementById('komame');
var fat = document.getElementById('stanley');
var img = document.querySelector('img');
fat.onclick = function () {
img.src = 'stanley.jpg';
img.title = '史丹利';
};
mouse.onclick = function () {
img.src = 'komame.jpg';
img.title = '茸茸鼠';
};
</script>
</body>
```
## 分時問候案例
```
<body>
<img src="sun.jpg" alt="" />
<div>早安</div>
<script>
// 1.獲取元素
var img = document.querySelector('img');
var div = document.querySelector('div');
// 2.獲取時間
var date = new Date();
var h = date.getHours();
// 3.判斷時間
if (h < 12) {
img.src = 'sun.jpg';
div.innerHTML = '早安';
} else if (h < 18) {
img.src = 'sunset.jpg';
div.innerHTML = '午安';
} else {
img.src = 'moon.jpg';
div.innerHTML = '晚安';
}
</script>
</body>
```
## 操作表單
type
value
ckecked
selected
disabled
```
<body>
<button>按鈕</button>
<input type="text" value="輸入內容" />
<script>
var btn = document.querySelector('button');
var input = document.querySelector('input');
btn.onclick = function () {
// input.innerHTML = '點擊了'; // 不能這樣寫
input.value = '被點擊了';
// btn.disabled = true;
this.disabled = true;
};
</script>
</body>
```
```
<!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>
.box {
position: relative;
width: 400px;
border-bottom: 1px solid #ccc;
margin: 100px auto;
}
.box input {
width: 370px;
height: 30px;
border: 0;
outline: none;
}
.box img {
position: absolute;
top: 2px;
right: 2px;
width: 24px;
}
</style>
</head>
<body>
<div class="box">
<label for="">
<img src="close.jpg" alt="" id="eye" />
</label>
<input type="password" name="" id="pwd" />
</div>
<script>
var eye = document.getElementById('eye');
var pwd = document.getElementById('pwd');
var flag = 0;
eye.onclick = function () {
if (flag == 0) {
pwd.type = 'text';
eye.src = 'open.jpg';
flag = 1;
} else {
pwd.type = 'password';
eye.src = 'close.jpg';
flag = 0;
}
};
</script>
</body>
</html>
```
## 修改樣式
通過JS修改元素大小、顏色、位置
element.style 行內樣式操作
element.className 類名樣式操作
注意
駝峰命名:fontSize、backgroundColor
產生行內式:css權重高
```
<!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>
div {
width: 200px;
height: 200px;
background-color: pink;
}
</style>
</head>
<body>
<div></div>
<script>
var div = document.querySelector('div');
div.onclick = function () {
this.style.backgroundColor = 'purple';
this.style.width = '250px';
};
</script>
</body>
</html>
```
## 淘寶二維碼
```
<!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>
.box {
position: relative;
width: 74px;
height: 88px;
border: 1px solid #ccc;
margin: 100px auto;
font-size: 12px;
text-align: center;
color: #f40;
/* display: block; */
}
.box img {
width: 60px;
margin-top: 5px;
}
.close-btn {
position: absolute;
top: -1px;
left: -16px;
width: 14px;
height: 14px;
border: 1px solid #ccc;
line-height: 14px;
font-family: Arial, Helvetica, sans-serif;
cursor: pointer;
}
</style>
</head>
<body>
<div class="box">
淘寶二維碼
<img src="tao.jpg" alt="" />
<i class="close-btn">x</i>
</div>
<script>
var btn = document.querySelector('.close-btn');
var box = document.querySelector('.box');
btn.onclick = function () {
box.style.display = 'none';
};
</script>
</body>
</html>
```
## 輪播精靈圖
```
<!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>
* {
margin: 0;
padding: 0;
}
li {
list-style-type: none;
}
.box {
width: 250px;
margin: 100px auto;
}
.box li {
float: left;
width: 24px;
height: 24px;
background-color: pink;
margin: 15px;
background: url(elf.jpg) no-repeat;
}
</style>
</head>
<body>
<div class="box">
<ul>
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
</ul>
</div>
<script>
var lis = document.querySelectorAll('li');
for (var i = 0; i < lis.length; i++) {
var index = i * 48;
lis[i].style.backgroundPosition = '0-' + index + 'px';
}
</script>
</body>
</html>
```
## 顯示隱藏文本框
```
<!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>
input {
color: #999;
}
</style>
</head>
<body>
<input type="text" value="手機" />
<script>
var text = document.querySelector('input');
text.onfocus = function () {
console.log('得到了焦點');
if (this.value === '手機') {
this.value = '';
}
this.style.color = '#333';
};
text.onblur = function () {
console.log('失去了焦點');
if (this.value === '') {
this.value = '手機';
this.style.color = '#999';
}
};
</script>
</body>
</html>
```
## className
```
<!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>
div {
width: 100px;
height: 100px;
background-color: pink;
}
.change {
background-color: purple;
color: #fff;
font-size: 25px;
margin-top: 100px;
}
</style>
</head>
<body>
<div class="first">文本</div>
<script>
var test = document.querySelector('div');
test.onclick = function () {
// this.style.backgroundColor = 'purple';
// this.style.color = '#fff';
// this.style.fontSize = '25px';
// this.style.marginTop = '100px';
// this.className = 'change'; // 原本的會被覆蓋
this.className = 'first change';
};
</script>
</body>
</html>
```
## 密碼框驗證訊息
```
<!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>
div {
width: 600px;
margin: 100px auto;
}
.message {
display: inline-block;
font-size: 12px;
color: #999;
background: url(mess.jpg) no-repeat left center;
padding-left: 20px;
}
.wrong {
color: red;
background-image: url(wrong.jpg);
}
.right {
color: green;
background-image: url(right.jpg);
}
</style>
</head>
<body>
<div class="register">
<input type="password" class="ipt" />
<p class="message">請輸入6~16位密碼</p>
</div>
<script>
var ipt = document.querySelector('.ipt');
var message = document.querySelector('.message');
ipt.onblur = function () {
if (this.value.length < 6 || this.value.length > 16) {
console.log('錯誤');
message.className = 'message wrong';
message.innerHTML = '你輸入的位數不是6~16位';
} else {
message.className = 'message right';
message.innerHTML = '輸入正確';
}
};
</script>
</body>
</html>
```
## 排他思想
注意
for循環的i
有全局變量與局部變量
```
<!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>
</head>
<body>
<button>按鈕1</button>
<button>按鈕2</button>
<button>按鈕3</button>
<button>按鈕4</button>
<button>按鈕5</button>
<script>
var btns = document.getElementsByTagName('button');
// btns得到的是偽數組 裡面每個元素btns[i]
for (var i = 0; i < btns.length; i++) {
btns[i].onclick = function () {
for (var i = 0; i < btns.length; i++) {
btns[i].style.backgroundColor = '';
}
this.style.backgroundColor = 'pink';
};
}
</script>
</body>
</html>
```
## 網頁換膚
```
<!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>
* {
margin: 0;
padding: 0;
}
body {
background: url(bg1.jpg) no-repeat center top;
}
li {
list-style: none;
}
.baidu {
overflow: hidden;
margin: 100px auto;
background-color: #fff;
width: 410px;
padding-top: 3px;
}
.baidu li {
float: left;
margin: 0 1px;
cursor: pointer;
}
.baidu img {
width: 100px;
}
</style>
</head>
<body>
<ul class="baidu">
<li><img src="bg1.jpg" /></li>
<li><img src="bg2.jpg" /></li>
<li><img src="bg3.jpg" /></li>
<li><img src="bg4.jpg" /></li>
</ul>
<script>
var imgs = document.querySelector('.baidu').querySelectorAll('img');
for (var i = 0; i < imgs.length; i++) {
imgs[i].onclick = function () {
document.body.style.backgroundImage = 'url(' + this.src + ')';
};
}
</script>
</body>
</html>
```
## 隔行變色
```
<!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>
thead tr {
height: 30px;
background-color: skyblue;
}
tbody tr {
height: 30px;
}
tbody td {
border-bottom: 1px solid #d7d7d7;
font-size: 12px;
color: blue;
}
.bg {
background-color: pink;
}
</style>
</head>
<body>
<table>
<thead>
<tr>
<th>代碼</th>
<th>名稱</th>
<th>最新公布淨值</th>
<th>累計淨值</th>
<th>前單位淨值</th>
<th>淨值增長率</th>
</tr>
</thead>
<tbody>
<tr>
<td>003526</td>
<td>定期開放債卷</td>
<td>1.075</td>
<td>1.079</td>
<td>1.074</td>
<td>+0.047%</td>
</tr>
<tr>
<td>003526</td>
<td>定期開放債卷</td>
<td>1.075</td>
<td>1.079</td>
<td>1.074</td>
<td>+0.047%</td>
</tr>
<tr>
<td>003526</td>
<td>定期開放債卷</td>
<td>1.075</td>
<td>1.079</td>
<td>1.074</td>
<td>+0.047%</td>
</tr>
<tr>
<td>003526</td>
<td>定期開放債卷</td>
<td>1.075</td>
<td>1.079</td>
<td>1.074</td>
<td>+0.047%</td>
</tr>
<tr>
<td>003526</td>
<td>定期開放債卷</td>
<td>1.075</td>
<td>1.079</td>
<td>1.074</td>
<td>+0.047%</td>
</tr>
<tr>
<td>003526</td>
<td>定期開放債卷</td>
<td>1.075</td>
<td>1.079</td>
<td>1.074</td>
<td>+0.047%</td>
</tr>
</tbody>
</table>
<script>
var trs = document.querySelector('tbody').querySelectorAll('tr');
for (var i = 0; i < trs.length; i++) {
trs[i].onmouseover = function () {
this.className = 'bg';
};
trs[i].onmouseout = function () {
this.className = '';
};
}
</script>
</body>
</html>
```
## 表單全選取消全選
```
<!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>
</head>
<body>
<div class="wrap">
<table>
<thead>
<tr>
<th>
<input type="checkbox" id="j_cbAll" />
</th>
<th>商品</th>
<th>價錢</th>
</tr>
</thead>
<tbody id="j_tb">
<tr>
<td>
<input type="checkbox" />
</td>
<td>iphone</td>
<td>8000</td>
</tr>
<tr>
<td>
<input type="checkbox" />
</td>
<td>iphone</td>
<td>8000</td>
</tr>
<tr>
<td>
<input type="checkbox" />
</td>
<td>iphone</td>
<td>8000</td>
</tr>
<tr>
<td>
<input type="checkbox" />
</td>
<td>iphone</td>
<td>8000</td>
</tr>
</tbody>
</table>
</div>
<script>
var j_cbAll = document.getElementById('j_cbAll');
var j_tbs = document.getElementById('j_tb').getElementsByTagName('input');
j_cbAll.onclick = function () {
console.log(this.checked);
for (var i = 0; i < j_tbs.length; i++) {
j_tbs[i].checked = this.checked;
}
};
for (var i = 0; i < j_tbs.length; i++) {
j_tbs[i].onclick = function () {
var flag = true;
for (var i = 0; i < j_tbs.length; i++) {
if (!j_tbs[i].checked) {
flag = false;
break; // 提高執行效率
}
}
j_cbAll.checked = flag;
};
}
</script>
</body>
</html>
```
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