Custom Objects in JS
A custom object of the form Object
Object definition:
var variable name = new Object(); // object instance (empty object)
variable name. attribute name = value; // define an attribute
variable name. function name = function(){} // define a function
Object access:
variable name.property/function name();
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script type="text/javascript">
// 对象的定义：
// var 变量名 = new Object(); // 对象实例（空对象）
// 变量名.属性名 = 值; // 定义一个属性
// 变量名.函数名 = function(){} // 定义一个函数
var obj = new Object();
obj.name = "华仔";
obj.age = 18;
obj.fun = function () {
alert("姓名：" + this.name + " , 年龄：" + this.age);
}
// 对象的访问：
// 变量名.属性 / 函数名();
// alert( obj.age );
obj.fun();
</script>
</head>
<body>
</body>
</html>
Custom objects in {} curly braces
Object definition:
var variable name = { // empty object
Attribute name: value, // define an attribute
Attribute name: value, // define an attribute
Function name: function(){} // define a function
};
Object access:
variable name.property/function name();
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script type="text/javascript">
// 对象的定义：
// var 变量名 = { // 空对象
// 属性名：值, // 定义一个属性
// 属性名：值, // 定义一个属性
// 函数名：function(){} // 定义一个函数
// };
var obj = {
name:"国哥",
age:18,
fun : function () {
alert("姓名：" + this.name + " , 年龄：" + this.age);
}
};
// 对象的访问：
// 变量名.属性 / 函数名();
alert(obj.name);
obj.fun();
</script>
</head>
<body>
</body>
</html>
events in js
What is an event? Events are responses to computer input devices interacting with the page. We call them events.
Commonly used events:
- onload loading completion event: After the page is loaded, it is often used to initialize the page js code
- onclick Click event: Commonly used for button click response operations.
- onblur focus loss event: It is commonly used to verify whether the input content is legal after the input box loses focus.
- onchange Content change event: It is often used to operate after the content of the drop-down list and input box changes
- onsubmit Form submission event: It is often used to verify whether all form items are legal before the form is submitted.
Event registration is divided into static registration and dynamic registration:
What is event registration (binding)?
In fact, it is to tell the browser what operation codes to execute after the event is responded to, which is called event registration or event binding.
Static registration event:
The event attribute of the html tag is directly assigned to the code after the event response. This method is called static registration.
Dynamic registration event:
means to get the dom object of the label through js code first, and then pass
dom object.event name = function(){} This form is assigned to the code after the event response, which is called dynamic registration.
Basic steps of dynamic registration:
1. Get the label object
2. Label object.Event name = fucntion(){}
onload load complete
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script type="text/javascript">
// onload 事件的方法
function onloadFun() {
alert('静态注册 onload 事件，所有代码');
}
// onload 事件动态注册。是固定写法
window.onload = function () {
alert("动态注册的 onload 事件");
}
</script>
</head>
<!--静态注册 onload 事件
onload 事件是浏览器解析完页面之后就会自动触发的事件
<body οnlοad="onloadFun();">-->
<body>
</body>
</html>
onclick click event
get label object
- document is an object (document) provided by JavaScript language
get get
Element element (that is, label)
By pass. . Depend on. . through. . .
Id id attribute
getElementById Get the tag object through the id attribute
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script type="text/javascript">
function onclickFun() {
alert("静态注册 onclick 事件");
}
// 动态注册 onclick 事件
window.onload = function () {
// 1 获取标签对象
/*
* document 是 JavaScript 语言提供的一个对象（文档）<br/>
* get 获取
* Element 元素（就是标签）
* By 通过。。 由。。经。。。
* Id id 属性
*
* getElementById 通过 id 属性获取标签对象
**/
var btnObj = document.getElementById("btn01");
// alert( btnObj );
// 2 通过标签对象.事件名 = function(){}
btnObj.onclick = function () {
alert("动态注册的 onclick 事件");
}
}
</script>
</head>
<body>
<!--静态注册 onClick 事件-->
<button onclick="onclickFun();">按钮 1</button>
<button id="btn01">按钮 2</button>
</body>
</html>
onchange content change event
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script type="text/javascript">
function onchangeFun() {
alert("女神已经改变了");
}
window.onload = function () {
//1 获取标签对象
var selObj = document.getElementById("sel01");
// alert( selObj );
//2 通过标签对象.事件名 = function(){}
selObj.onchange = function () {
alert("男神已经改变了");
}
}
</script>
</head>
<body>
请选择你心中的女神：
<!--静态注册 onchange 事件-->
<select onchange="onchangeFun();">
<option>--女神--</option>
<option>芳芳</option>
<option>佳佳</option>
<option>娘娘</option>
</select>
请选择你心中的男神：
<select id="sel01">
<option>--男神--</option>
<option>国哥</option>
<option>华仔</option>
<option>富城</option>
</select>
</body>
</html>
onsubmit form submission event
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script type="text/javascript">
// 静态注册表单提交事务
function onsubmitFun() {
// 要验证所有表单项是否合法，如果，有一个不合法就阻止表单提交
alert("静态注册表单提交事件----发现不合法");
return flase;
}
window.onload = function () {
//1 获取标签对象
var formObj = document.getElementById("form01");
//2 通过标签对象.事件名 = function(){}
formObj.onsubmit = function () {
// 要验证所有表单项是否合法，如果，有一个不合法就阻止表单提交
alert("动态注册表单提交事件----发现不合法");
return false;
}
}
</script>
</head>
<body>
<!--return false 可以阻止 表单提交 -->
<form action="http://localhost:8080" method="get" onsubmit="return onsubmitFun();">
<input type="submit" value="静态注册" />
</form>
<form action="http://localhost:8080" id="form01">
<input type="submit" value="动态注册" />
</form>
</body>
</html>