javascript惯用对象 _JavaScript

javascript常用对象

1.Date对象：

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
 <head>
  <title> New Document </title>
  <meta name="Generator" content="EditPlus">
  <meta name="Author" content="">
  <meta name="Keywords" content="">
  <meta name="Description" content="">
<script type="text/javascript">
  var date = new Date();
  document.write(date);
</script>
 </head>
 <body>
 </body>
</html>

运行结果：

我们来改变一下输出的方式：

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
 <head>
  <title> New Document </title>
  <meta name="Generator" content="EditPlus">
  <meta name="Author" content="">
  <meta name="Keywords" content="">
  <meta name="Description" content="">
<script type="text/javascript">
  var date = new Date();
  document.write(date.getFullYear()+"年"+date.getMonth()+"月"+date.getDate()+"日");
</script>
 </head>
 <body>
 </body>
</html>

运行结果：

明明是9月，却显示的是8月，说明getMonth是从下标0开始的，所以要加1：

 document.write(date.getFullYear()+"年"+(date.getMonth()+1)+"月"+date.getDate()+"日");

这样就会输出正确的结果了。

2.String对象：

2.1

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
 <head>
  <title> New Document </title>
  <meta name="Generator" content="EditPlus">
  <meta name="Author" content="">
  <meta name="Keywords" content="">
  <meta name="Description" content="">
<script type="text/javascript">
  var str1 = new String("niujiabin");
  var str2 = "niujiabin";
  alert(str1==str2);
</script>
 </head>
 <body>
 </body>
</html>

结果是true，这里与java是有区别的，并不存在引用，没有equals方法。

2.2字符串连接

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title> New Document </title>
<meta name="Generator" content="EditPlus">
<meta name="Author" content="">
<meta name="Keywords" content="">
<meta name="Description" content="">
<script type="text/javascript">
var str1 = new String("niujiabin");
var str2 = "niujiabin";
// alert(str1==str2);
//字符串的连接
var str3 = str2.concat("maybe","gossip");
alert(str3);
</script>
</head>
<body>
</body>
</html>

连接字符串，concat的参数没有限制，随便连就可以了，输出结果：

2.3字符串截取

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
 <head>
  <title> New Document </title>
  <meta name="Generator" content="EditPlus">
  <meta name="Author" content="">
  <meta name="Keywords" content="">
  <meta name="Description" content="">
  <script type="text/javascript">
//字符串截取
var str1 = "niujiabinbin";
var str2 = str1.slice(3,6);
alert(str2);
</script>
 </head>

 <body>
  
 </body>
</html>

运行结果：

2.4字符串选取substring与substr

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
 <head>
  <title> New Document </title>
  <meta name="Generator" content="EditPlus">
  <meta name="Author" content="">
  <meta name="Keywords" content="">
  <meta name="Description" content="">
  <script type="text/javascript">
   var str1 = "niujiabinbin";
   document.write(str1.substring(2,9)+"<br>");
   document.write(str1.substr(2,9));
</script>
 </head>

 <body>
  
 </body>
</html>

运行结果：

区别在于substring是下标2-9，而substr是从下标2开始，选取9个字符。

3.array对象：

js中的array对象其实就是java中的List和Stack集合

3.1

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
 <head>
  <title> New Document </title>
  <meta name="Generator" content="EditPlus">
  <meta name="Author" content="">
  <meta name="Keywords" content="">
  <meta name="Description" content="">
  <script type="text/javascript">
  //第一种定义方式
  var a1 =new Array();
  a1.push(11);
  a1.push(12);
  document.write(a1+"<br>");

  //第二种定义方式
  var a2 = new Array("niujiabin","1",1);
  document.write(a2+"<br>");
   
  //第三种定义方式,一般都采用这种方式
  var a3=["maybe",1,"1"];
  document.write(a3+"<br>");
</script>
 </head>
 <body>  
 </body>
</html>

输出结果：

输出结果的分割形式都是逗号，我们当然也可以改变，只需通过join方法：

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
 <head>
  <title> New Document </title>
  <meta name="Generator" content="EditPlus">
  <meta name="Author" content="">
  <meta name="Keywords" content="">
  <meta name="Description" content="">
  <script type="text/javascript">
  //第一种定义方式
  var a1 =new Array();
  a1.push(11);
  a1.push(12);
  document.write(a1.join("-")+"<br>");

  //第二种定义方式
  var a2 = new Array("niujiabin","1",1);
  document.write(a2.join("_")+"<br>");
   
  //第三种定义方式,一般都采用这种方式
  var a3=["maybe",1,"1"];
  document.write(a3.join("***")+"<br>");
</script>
 </head>
 <body>  
 </body>
</html>

运行结果：

3.2 sort方法：

这个方法只会根据字符串来排序：

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
 <head>
  <title> New Document </title>
  <meta name="Generator" content="EditPlus">
  <meta name="Author" content="">
  <meta name="Keywords" content="">
  <meta name="Description" content="">
  <script type="text/javascript">

  var a3=[1111,111,12,443,44,555,5555,67,76];
  document.write(a3.sort());
</script>
 </head>
 <body>  
 </body>
</html>

排序结果：

array的方法还有pop，shift，onshift等对栈和队列的相关操作，还有splice插入元素，这里就不一一介绍了。