table of Contents
Chapter IV, BOM and the front of the DOM
First, explain BOM and DOM
BOM (Browser Object Model) refers to the browser object model that enables JavaScript capable browser to "talk."
DOM (Document Object Model) refers to the document object model, through which you can access all the elements of the HTML document.
Two, window objects
window.innerHeight - 浏览器窗口的内部高度
window.innerWidth - 浏览器窗口的内部宽度
window.open() - 打开新窗口
window.close() - 关闭当前窗口Three, window sub-objects
navigator对象
sreen对象
history对象
location对象Fourth, the pop-up box
警告框：alert()
确认框: confirm() 返回true和false
提示框 ：prompt() 返回输入的值Fifth, the timing-related
setTimeout("js代码",毫秒) 返回某个值 过了一段时间执行
clearTimesetT(setTimeout返回的值)
setInterval("js代码",毫秒) 每隔一段时间执行js语句，返回的是ID值，该值可用作 clearInterval() 方法的参数。
clearInterval(setinterval返回的ID值) 方法可取消由 setInterval() 设置的 timeout。ps: the above is DOM, following a BOM
Six, HTML DOM tree
Description: the DOM standard specifies that each component of an HTML document is a node (node):
- Document node (document object): On behalf of the entire document
- Element node (element object): represents an element (tag)
- Node text (text object): Representative elements (tags) in the text
- Node attribute (attribute objects): represents an attribute element (tag) have properties
- Comments are comment nodes (comment Object)
Description : JavaScript can create dynamic HTML through DOM:
- JavaScript can change all the HTML elements on the page
- JavaScript can change the properties of all HTML pages
- JavaScript can change all CSS styles page
- JavaScript can react to all events page
Seven, find elements
直接查找：
document.getElementById 根据ID获取一个标签
document.getElementsByClassName 根据class属性获取
document.getElementsByTagName 根据标签名获取标签合集
间接查找：
parentElement 父节点标签元素
children 所有子标签
firstElementChild 第一个子标签元素
lastElementChild 最后一个子标签元素
nextElementSibling 下一个兄弟标签元素
previousElementSibling 上一个兄弟标签元素Eight node operation
创建节点
createElement(标签名)1.html
<!--创建一个新的<div>并且插入到ID为“div1”的元素前。-->
<!DOCTYPE html>
<html>
<head>
<title>||Working with elements||</title>
</head>
<body>
<div id="div1">The text above has been created dynamically.</div>
</body>
</html>在控制台上输入
document.body.onload = addElement;
function addElement () {
// create a new div element
// and give it some content
var newDiv = document.createElement("div");
var newContent = document.createTextNode("Hi there and greetings!");
newDiv.appendChild(newContent); //add the text node to the newly created div.
// add the newly created element and its content into the DOM
var currentDiv = document.getElementById("div1");
document.body.insertBefore(newDiv, currentDiv);
}
addElement()
The results are as follows
html文本
<html><head>
<title>||Working with elements||</title>
</head>
<body>
<div>Hi there and greetings!</div>
<div>Hi there and greetings!</div><div id="div1">The text above has been created dynamically.</div>
</body></html>
显示效果：
Hi there and greetings!
The text above has been created dynamically.添加节点
追加一个子节点（作为最后的子节点）
somenode.appendChild(newnode)；
把增加的节点放到某个节点的前边。
somenode.insertBefore(newnode,某个节点);
-------------------------------------------
实例：
document.getElementById("myList").insertBefore(newItem,existingItem);替换节点：
somenode.replaceChild(newnode, 某个节点);属性节点
获取文本节点的值：
var divEle = document.getElementById("d1")
divEle.innerText
divEle.innerHTML设置文本节点的值：
var divEle = document.getElementById("d1")
divEle.innerText="1"
divEle.innerHTML="<p>2</p>"attribute操作
var divEle = document.getElementById("d1");
divEle.setAttribute("age","18")
divEle.getAttribute("age")
divEle.removeAttribute("age")
// 自带的属性还可以直接.属性名来获取和设置
imgEle.src
imgEle.src="..."获取值操作
节点对象.value
适用于以下标签：
.input
.select
.textarea
------------------------------
var iEle = document.getElementById("i1");
console.log(iEle.value);
var sEle = document.getElementById("s1");
console.log(sEle.value);
var tEle = document.getElementById("t1");
console.log(tEle.value);class的操作
className 获取所有样式类名(字符串)
classList.remove(cls) 删除指定类 classList.add(cls) 添加类
classList.contains(cls) 存在返回true，否则返回false
classList.toggle(cls) 存在就删除，否则添加指定CSS操作
obj.style.backgroundColor="red"Nine, JS CSS property law operation
For CSS property is not used directly in the horizontal line of the general style. Attribute name. Such as:
obj.style.margin
obj.style.width
obj.style.left
obj.style.position
CSS properties of the horizontal line containing the first letter after the horizontal line can be made uppercase. Such as:
obj.style.marginTop
obj.style.borderLeftWidth
obj.style.zIndex
obj.style.fontFamily
Ten, Event
onclick 当用户点击某个对象时调用的事件句柄。
ondblclick 当用户双击某个对象时调用的事件句柄。
onfocus 元素获得焦点。 // 练习：输入框
onblur 元素失去焦点。 应用场景：用于表单验证,用户离开某个输入框时,代表已经输入完了,我们可以对它进行验证.
onchange 域的内容被改变。 应用场景：通常用于表单元素,当元素内容被改变时触发.（select联动）
onkeydown 某个键盘按键被按下。 应用场景: 当用户在最后一个输入框按下回车按键时,表单提交.
onkeypress 某个键盘按键被按下并松开。
onkeyup 某个键盘按键被松开。
onload 一张页面或一幅图像完成加载。
onmousedown 鼠标按钮被按下。
onmousemove 鼠标被移动。
onmouseout 鼠标从某元素移开。Binding way
Method 1: Define the label when he designated the good function
<div id="d1" onclick="changeColor(this);">点我</div> <script> function changeColor(this) { ths.style.backgroundColor="green"; } </script>note:
this is an argument that is the current element that triggered the event.
Function definition during ths as parameter.
Second way: after a defined tag specifies an object property functions embodiment
<div id="d2">点我</div> <script> var divEle2 = document.getElementById("d2"); divEle2.onclick=function () { this.innerText="呵呵"; } </script>
X. Case
Timer:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<meta name="viewport" content="width=device-width, initial-scale=1">
</head>
<body>
<input type="text" id="i1">
<button id="b1">开始</button>
<button id="b2">结束</button>
<script>
var t;
function showTime() {
var i1Ele = document.getElementById('i1');
var time = new Date();
i1Ele.value = time.toLocaleString();
}
showTime();
var b1Ele = document.getElementById('b1');
b1Ele.onclick = function (ev) {
if (!t){
t = setInterval(showTime,1000)
}
};
var b2Ele = document.getElementById('b2');
b2Ele.onclick = function (ev) {
clearInterval(t);
t = undefined
};
</script>
</body>
</html>Knowledge related to: timing-related functions, onclick event is triggered, find elements, use the Date object, input label
search bar
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>搜索框示例</title>
</head>
<body>
<input id="d1" type="text" value="请输入关键字" onblur="blur()" onfocus="focus()">
<script>
function focus(){
var inputEle=document.getElementById("d1");
if (inputEle.value==="请输入关键字"){
inputEle.value="";
}
}
function blur(){
var inputEle=document.getElementById("d1");
var val=inputEle.value;
if(!val.trim()){
inputEle.value="请输入关键字";
}
}
</script>
</body>
</html>Related to knowledge: Get the property value method, find an element, onfocus, onblur property