JavaScript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>

image.png

<!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>

image.png

<!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>

image.png

<!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>

image.png

<!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>

image.png

<!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>

image.png

<!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>

image.png

<!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>

image.png

<!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>

image.png

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:

image

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;
        width:230px;
        height:50px;
        background:#ccc;
        color:red;
    }
    .two{
        border:1px solid #ccc;
        width: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;
    width: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>

本文参与腾讯云自媒体分享计划,欢迎正在阅读的你也加入,一起分享。

发表于

我来说两句

0 条评论
登录 后参与评论

扫码关注云+社区

领取腾讯云代金券