js原生创建模拟事件和自定义事件的方法
让我万万没想到的是,原来《JavaScript高级程序设计(第3版)》里面提到的方法已经是过时的了.后来我查看了MDN,才找到了最新的方法.
1. 模拟鼠标事件
MDN上已经说得很清楚,尽管为了保持向后兼容MouseEvent.initMouseEvent()仍然可用,但是呢,我们应该使用MouseEvent().
我们使用如下页面做测试
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1"/>
<title></title>
<style>
.button {
width: 200px;
height: 200px;
background-color: antiquewhite;
margin: 20px;
text-align: center;
line-height: 200px;
}
</style>
</head>
<body>
<div>Button</div>
<script>
"use strict";
var btn = document.querySelector('.button');
btn.addEventListener('click', function (event) {
console.log('OH~!You clicked me~!');
}, false);
var ev = new MouseEvent('click', {
cancelable: true,
bubble: true,
view: window
});
btn.dispatchEvent(ev);
</script>
</body>
</html>
当然,在构建这个MouseEvent对象的时候还是有很多属性可以填写的,不过,可能就是示例的那几个比较有用,如果像查看更多的属性,请查看如下地址
(由于MouseEvent继承自UIEvent和Event,所以,他也继承了他们的属性)
https://developer.mozilla.org/en-US/docs/Web/API/MouseEvent
https://developer.mozilla.org/en-US/docs/Web/API/UIEvent
https://developer.mozilla.org/en-US/docs/Web/API/Event
想查看MouseEvent()构造器的具体用法,请查看
https://developer.mozilla.org/en-US/docs/Web/API/MouseEvent/MouseEvent
2. 模拟键盘事件
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1"/>
<title></title>
<style>
.button {
width: 200px;
height: 200px;
background-color: antiquewhite;
margin: 20px;
text-align: center;
line-height: 200px;
}
</style>
</head>
<body>
<div>Button</div>
<script>
"use strict";
var btn = document.querySelector('.button');
document.addEventListener('keyup', function (event) {
console.log(String.fromCharCode(event.keyCode));
}, false);
var ev = new KeyboardEvent('keyup', {
keyCode: 65
});
document.dispatchEvent(ev);
</script>
</body>
</html>
如下是KeyBoardEvent的详细说明
https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent
3. 自定义事件
自定义事件有两种方法,一种是使用new Event(),另一种是new customEvent()
1. new Event()
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1"/>
<title></title>
<style>
.button {
width: 200px;
height: 200px;
background-color: antiquewhite;
margin: 20px;
text-align: center;
line-height: 200px;
}
</style>
</head>
<body>
<div>Button</div>
<script>
"use strict";
var btn = document.querySelector('.button');
var ev = new Event('test', {
bubbles: 'true',
cancelable: 'true'
});
btn.addEventListener('test', function (event) {
console.log(event.bubbles);
console.log(event.cancelable);
console.log(event.detail);
}, false);
btn.dispatchEvent(ev);
</script>
</body>
</html>
运行效果如下所示,请先注意,event.detail的值为undefined
2. new customEvent()
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1"/>
<title></title>
<style>
.button {
width: 200px;
height: 200px;
background-color: antiquewhite;
margin: 20px;
text-align: center;
line-height: 200px;
}
</style>
</head>
<body>
<div>Button</div>
<script>
"use strict";
var btn = document.querySelector('.button');
var ev = new CustomEvent('test', {
bubbles: 'true',
cancelable: 'true',
detail: 'tcstory'
});
btn.addEventListener('test', function (event) {
console.log(event.bubbles);
console.log(event.cancelable);
console.log(event.detail);
}, false);
btn.dispatchEvent(ev);
</script>
</body>
</html>
效果如下图
可以很明显的看到,其实new customEvent()比new Event()多了可以在event.detail属性里携带自定义数据的功能(event.detail的值为tcstory),这就是差别了.
Event()的详细说明
https://developer.mozilla.org/en-US/docs/Web/API/Event/Event
customEvent() 的详细说明
https://developer.mozilla.org/en-US/docs/Web/API/CustomEvent
4. 总结
总结下来发现,除了模拟自定义事件比较有用的话,模拟鼠标事件和键盘事件则好像有点坑和不一致性.以模拟键盘事件来说吧.
KeyboardEvent.key在MDN上的文档被提示为推荐使用的属性,而KeyboardEvent.keyCode却被说成是不推荐使用的,应该使用key属性,然而你去看KeyboardEvent.key的文档就会发现,这个属性压根就没得到多少浏览器的支持,如果用这个属性,简直就是掉坑里了.
下图所示,一大片的红字啊
