JavaScript的入门篇

快速认识JavaScript
熟悉JavaScript基本语法
窗口交互方法
通过DOM进行网页元素的操作
学会如何编写JS代码
运用JavaScript去操作HTML元素和CSS样式

<!DOCTYPE HTML>
<html> 
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>热身</title>
</head>
<body>
  <p id="p1">我是第一段文字</p>
  <p id="p2">我是第二段文字</p>
  
  <script type="text/javascript">
	document.write("hello");
	document.getElementById("p1").style.color="blue"; 
  </script>
</body>
</html>

[外链图片转存失败(img-suQFlZh3-1564302201976)(https://upload-images.jianshu.io/upload_images/11158618-67dcaa8a99832105.png?imageMogr2/auto-orient/strip|imageView2/2/w/1240)]

<!DOCTYPE HTML>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=gb18030">
        <title>插入js代码</title>
        <script type="text/javascript">
        document.write("开启JS之旅!");
    </script>
    </head>
    <body>
    </body>
</html>

[外链图片转存失败(img-vu9DMpGY-1564302201978)(https://upload-images.jianshu.io/upload_images/11158618-3f5db18412ba15e9.png?imageMogr2/auto-orient/strip|imageView2/2/w/1240)]

<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>引用JS文件</title>
<script src="script.js"></script>
</head>
<body>
</body>
</html>

<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>JS代码的位置</title>
<script type="text/javascript">
  document.write("I love");
</script>
</head>
<body>
<script type="text/javascript">
 document.write("javascript");
</script>
</body>
</html>

[外链图片转存失败(img-pFvvXb3U-1564302201980)(https://upload-images.jianshu.io/upload_images/11158618-22bea5891e5ebbd4.png?imageMogr2/auto-orient/strip|imageView2/2/w/1240)]

<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>认识语句</title>
<script type="text/javascript">
document.write("Hello");
 document.write("world");
</script>
</head>
<body>
</body>
</html>

[外链图片转存失败(img-96XJYpJO-1564302201980)(https://upload-images.jianshu.io/upload_images/11158618-d250649483e98538.png?imageMogr2/auto-orient/strip|imageView2/2/w/1240)]

<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>隐藏的注释</title>
 <script type="text/javascript">
    document.write("神奇的JS,快把我们隐藏了!"); //  快快把我变成单行注释
    /*知道吗
    JS可以实现很多动态效果
    快来学习吧!*/
 </script>
</head>
<body>
</body>
</html>

[外链图片转存失败(img-8DEDHucN-1564302201982)(https://upload-images.jianshu.io/upload_images/11158618-3b8f7aa75f39bbc9.png?imageMogr2/auto-orient/strip|imageView2/2/w/1240)]

<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>变量</title>
<script type="text/javascript">
 var mynum = 8;
</script>
</head>
<body>
</body>
</html>

<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>判断语句</title>
  <script type="text/javascript">
	var score =80; //score变量存储成绩，初值为80
	  if(score>80)
	{
     document.write("很棒，成绩及格了。");
	}
  else
	{
	 document.write("加油，成绩不及格。");
	}
  </script>
</head>
<body>
</body>
</html>

[外链图片转存失败(img-Mb0XgWyN-1564302201984)(https://upload-images.jianshu.io/upload_images/11158618-348a707a1a92570f.png?imageMogr2/auto-orient/strip|imageView2/2/w/1240)]

<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>函数调用</title>
   <script type="text/javascript">
      function contxt() //定义函数
      {
         alert("哈哈，调用函数了!");
      }
   </script>
</head>
<body>
   <form>
      <input type="button"  value="点击我" onclick="contxt()" />  
   </form>
</body>
</html>

[外链图片转存失败(img-3Hi1jdZD-1564302201986)(https://upload-images.jianshu.io/upload_images/11158618-a78fd94f2fe1b1b4.png?imageMogr2/auto-orient/strip|imageView2/2/w/1240)]

<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>document.write</title>
  <script type="text/javascript">
    var mystr="我是";
    var mychar="JavaScript";
document.write(mychar+"<br>");
document.write(mystr+mychar+"的忠实粉丝!")
  </script>
</head>
<body>
</body>
</html>

[外链图片转存失败(img-4gCtVAQU-1564302201988)(https://upload-images.jianshu.io/upload_images/11158618-e7114534d269d8fd.png?imageMogr2/auto-orient/strip|imageView2/2/w/1240)]

<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>alert</title>
  <script type="text/javascript">
  function rec(){
    var mychar="I love JavaScript";
    alert(mychar)
  }
  </script>
</head>
<body>
    <input name="button" type="button" onClick="rec()" value="点击我，弹出对话框" />
</body>
</html>

<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>alert</title>
  <script type="text/javascript">
  function rec(){
    var mychar="I love JavaScript";
    alert(mychar)
  }
  </script>
</head>
<body>
    <input name="button" type="button" onClick="rec()" value="点击我，弹出对话框" />
</body>
</html>

<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>confirm</title>
  <script type="text/javascript">
  function rec(){
    var mymessage= confirm("你是女士吗?");
    if(mymessage==true)
    {
    	document.write("你是女士!");
    }
    else
    {
        document.write("你是男士!");
    }
  }    
  </script>
</head>
<body>
    <input name="button" type="button" onClick="rec()" value="点击我，弹出确认对话框" />
</body>
</html>

<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>prompt</title>
  <script type="text/javascript">
  function rec(){
	var score; //score变量，用来存储用户输入的成绩值。
	score =  prompt("你的分数是多少？");
	if(score>=90)
	{
	   document.write("你很棒!");
	}
	else if(score>=75)
    {
	   document.write("不错吆!");
	}
	else if(score>=60)
    {
	   document.write("要加油!");
    }
    else
	{
       document.write("要努力了!");
	}
  }
  </script>
</head>
<body>
    <input name="button" type="button" onClick="rec()" value="点击我，对成绩做评价!" />
</body>
</html>

<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>window.open</title>
<script type="text/javascript">
  function Wopen(){
      window.open('http://www.123.com','_blank','height=600,width=400,top=100,left=0');

  } 
</script>
</head>
<body>
    <input name="button" type="button" onClick="Wopen()" value="点击我，打开新窗口!" / >
</body>
</html>

[外链图片转存失败(img-d3h6IynX-1564302201989)(https://upload-images.jianshu.io/upload_images/11158618-632c6710eac6846d.png?imageMogr2/auto-orient/strip|imageView2/2/w/1240)]

语法：

window.open([URL], [窗口名称], [参数字符串])

_blank：在新窗口显示目标网页
_self：在当前窗口显示目标网页
_top：框架网页中在上部窗口中显示目标网页

window.close(); //关闭本窗口
<窗口对象>.close(); //关闭指定的窗口

<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>close()</title>
  <script type="text/javascript">
     var mywin=window.open("http://www.123.com");
 mywin.close();
  </script>
</head>
<body>
</body>
</html>

<!DOCTYPE html>
<html>
 <head>
  <title> new document </title>  
  <meta http-equiv="Content-Type" content="text/html; charset=gbk"/>   
  <script type="text/javascript">  
    
    // 新窗口打开时弹出确认框，是否打开
function openWindow(){
var wep;
var op;
wep = confirm("是否打开新网页？");
if(wep==true)
{
op = prompt("默认网址为：","http://www.123.com/");
if(op!=null)
window.open(op,'_blank','width=400,height=500,menubar=no,toolbar=no');
}
else
alert("操作结束！！");

}
    // 通过输入对话框，确定打开的网址，默认为 http：//www.imooc.com/

    //打开的窗口要求，宽400像素，高500像素，无菜单栏、无工具栏。
    
    
  </script> 
 </head> 
 <body> 
	  <input type="button" value="新窗口打开网站" onclick="openWindow()" /> 
 </body>
</html>

HTML代码分解为DOM节点层次图:

[外链图片转存失败(img-C588ILaB-1564302201991)(https://upload-images.jianshu.io/upload_images/11158618-361ea0d15e0bddbc.jpg?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)]

通过ID获取元素
document.getElementById(“id”)

<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>document.getElementById</title>
</head>
<body>
<p id="con">JavaScript</p>
<script type="text/javascript">
  var mychar=           ;
  document.write("结果:"+mychar); //输出获取的P标签。 
  document.getElementById("con")
</script>
</body>
</html>

innerHTML 属性
innerHTML 属性用于获取或替换 HTML 元素的内容。

<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>innerHTML</title>
</head>
<body>
<h2 id="con">javascript</H2>
<p> JavaScript是一种基于对象、事件驱动的简单脚本语言，嵌入在HTML文档中，由浏览器负责解释和执行，在网页上产生动态的显示效果并实现与用户交互功能。</p>
<script type="text/javascript">
  var mychar=           ;
  document.write("原标题:"+mychar.innerHTML+"<br>"); //输出原h2标签内容
  document.getElementById("con")
  document.write("修改后的标题:"+mychar.innerHTML); //输出修改后h2标签内容
  mychar.innerHTML="Hello world";
</script>
</body>
</html>

改变 HTML 样式

语法:
Object.style.property=new style;

<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>style样式</title>
</head>
<body>
  <h2 id="con">I love JavaScript</H2>
  <p> JavaScript使网页显示动态效果并实现与用户交互功能。</p>
  <script type="text/javascript">
    var mychar= document.getElementById("con");
 mychar.style.color="red";
 mychar.style.backgroundColor ="#ccc";
mychar.style.width="300px";
  </script>
</body>
</html>

显示和隐藏（display属性）

<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>display</title>
    <script type="text/javascript"> 
        function hidetext()  
		{  
		var mychar = document.getElementById("con");
        mychar.style.display="none";
		}  
		function showtext()  
		{  
		var mychar = document.getElementById("con");
        mychar.style.display="block";
		}
    </script> 
</head> 
<body>  
    <h1>JavaScript</h1>  
    <p id="con">做为一个Web开发师来说，如果你想提供漂亮的网页、令用户满意的上网体验，JavaScript是必不可少的工具。</p> 
    <form>
       <input type="button" onclick="hidetext()" value="隐藏内容" /> 
       <input type="button" onclick="showtext()" value="显示内容" /> 
    </form>
</body> 
</html>

className 属性设置或返回元素的class 属性。

获取元素的class 属性

<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>className属性</title>
<style>
    body{ font-size:16px;}
    .one{
		border:1px solid #eee;
		230px;
		height:50px;
		background:#ccc;
		color:red;
    }
	.two{
		border:1px solid #ccc;
		230px;
		height:50px;
		background:#9CF;
		color:blue;
	}
	</style>
</head>
<body>
    <p id="p1" > JavaScript使网页显示动态效果并实现与用户交互功能。</p>
    <input type="button" value="添加样式" onclick="add()"/>
	<p id="p2" class="one">JavaScript使网页显示动态效果并实现与用户交互功能。</p>
    <input type="button" value="更改外观" onclick="modify()"/>

	<script type="text/javascript">
	   function add(){
	      var p1 = document.getElementById("p1");
	      p1.className = "one";
	   }
	   function modify(){
	      var p2 = document.getElementById("p2");
	      p2.className = "two";
	   }
	</script>
</body>
</html>

<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" Content="text/html; charset=utf-8" />
<title>javascript</title>
<style type="text/css">
body{font-size:12px;}
#txt{
    height:400px;
    600px;
	border:#333 solid 1px;
	padding:5px;}
p{
	line-height:18px;
	text-indent:2em;}
</style>
</head>
<body>
  <h2 id="con">JavaScript课程</H2>
  <div id="txt"> 
     <h5>JavaScript为网页添加动态效果并实现与用户交互的功能。</h5>
        <p>1. JavaScript入门篇，让不懂JS的你，快速了解JS。</p>
        <p>2. JavaScript进阶篇，让你掌握JS的基础语法、函数、数组、事件、内置对象、BOM浏览器、DOM操作。</p>
        <p>3. 学完以上两门基础课后，在深入学习JavaScript的变量作用域、事件、对象、运动、cookie、正则表达式、ajax等课程。</p>
  </div>
  <form>
  <!--当点击相应按钮，执行相应操作，为按钮添加相应事件-->
    <input type="button" value="改变颜色" >  
    <input type="button" value="改变宽高" >
    <input type="button" value="隐藏内容" >
    <input type="button" value="显示内容" >
    <input type="button" value="取消设置" >
  </form>
  <script type="text/javascript">
//定义"改变颜色"的函数
obj.style.color
obj.style.backgroundColor 

//定义"改变宽高"的函数
obj.style.width
obj.style.height 

//定义"隐藏内容"的函数
obj.style.display="none";

//定义"显示内容"的函数
obj.style.display="block";

//定义"取消设置"的函数
confirm()


  </script>
</body>
</html>

若本号内容有做得不到位的地方（比如：涉及版权或其他问题），请及时联系我们进行整改即可，会在第一时间进行处理。

请点赞！因为你们的赞同/鼓励是我写作的最大动力！

欢迎关注达叔小生的简书！

这是一个有质量，有态度的博客

[外链图片转存失败(img-z5uWZU0i-1564302201992)(https://upload-images.jianshu.io/upload_images/11158618-9ab0d3fef85d80ce?imageMogr2/auto-orient/strip|imageView2/2/w/1240)]

相关阅读:
服务管理--systemctl命令
 dd if=/dev/zero of=的含义是什么？Linux 下的dd命令使用详解
 QML与Qt C++ 交互机制探讨与总结
 sync命令
 linux 下shell中if的“-e，-d，-f”是什么意思
 POJ 1936 All in All（模拟）
POJ 1088 滑雪（记忆化搜索）
POJ 3280 Cheapest Palindrome（DP 回文变形）
POJ 3181 Dollar Dayz（高精度动态规划）
HDU 1114 Piggy-Bank（完全背包）
原文地址：https://www.cnblogs.com/dashucoding/p/11932334.html