<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
<style>
#box{
height: 200px;
width: 200px;
color: white;
background-color: orange;
}
</style>
</head>
<body>
<div style="text-align:center;" id="box">
<span style="font-size:20px;" id="txt">测试样例哈</span>
</div>
<script>
var box = document.getElementById("box");
var txt = document.getElementById("txt");
//1 .style.property 仅能获取内联样式 但可以修改样式
console.log(box.style.textAlign);//center
console.log(box.style.color);//空白
// box.style.color = "black";//√
//不可加！important
//2 .style.cssText
console.log(box.style.cssText);//text-align:center, 返回
// txt.style.cssText = "color:red;";//注意，会覆盖之前的样式，包括在这里没有写到的，相当于清除了原本元素的样式
//但是继承而来的样式不会被清除,如这里继承自box的居中对齐
//可加！important，如用来覆盖继承的属性
//3 .style.setProperty
txt.style.setProperty("font-size","30px");//√
//仅可用于部分常用属性
//4 document.defaultView(window).getComputedStyle
//IE则是currentStyle[attr]
var declaration = document.defaultView.getComputedStyle(box,null);
var detailStyle = document.defaultView.getComputedStyle(box,null).height;
// var declaration = document.defaultView.getComputedStyle(box,null)[height];//同理
var windowDeclaration = window.getComputedStyle(box,null);
console.log(declaration,windowDeclaration,detailStyle);
//4.sp 封装一个具有兼容性的属性查阅函数
function styleCheck (element,prop,state){
if(document.defaultView.getComputedStyle(element,state)){
result = document.defaultView.getComputedStyle(element,state)[prop];//不能.prop哈，记得
}else{
result = element.currentStyle.prop;
}
console.log("The value of property"+ prop + " is" + " " + result + ".");
return result;
}
styleCheck(box,"height");
//5. 对样式表下手 insertRule 与 addRule
// var changedStyleSheet = document.styleSheet[0].insertRule("#box","height","400px"); 插入新规则
</script>
</body>
</html>
