JS的正则表达

一 javascript正则表达式的基本知识

1     javascript 正则对象创建 和用法

    声明javascript 正则表达式
   
     var reCat = new RegExp("cat");
      你也可以
     var reCat = /cat/;      //Perl 风格   （推荐）

2 学习最常用的 test exec match search  replace  split 6个方法

   1） test  检查指定的字符串是否存在

       var data = "123123";
       var reCat = /123/gi;
       alert(reCat.test(data));  //true
     
       //检查字符是否存在  g 继续往下走  i 不区分大小写

   2） exec 返回查询值

       var data = "123123,213,12312,312,3,Cat,cat,dsfsdfs,";
       var reCat = /cat/i;
       alert(reCat.exec(data));  //Cat

     3）match  得到查询数组

       var data = "123123,213,12312,312,3,Cat,cat,dsfsdfs,";
       var reCat = /cat/gi;
       var arrMactches = data.match(reCat)

       for (var i=0;i < arrMactches.length ; i++)
       {
            alert(arrMactches);   //Cat  cat
       }

     4） search  返回搜索位置  类似于indexof

       var data = "123123,213,12312,312,3,Cat,cat,dsfsdfs,";
       var reCat = /cat/gi;
       alert(data.search(reCat));  //23


    5） replace  替换字符  利用正则替换

       var data = "123123,213,12312,312,3,Cat,cat,dsfsdfs,";
       var reCat = /cat/gi;
       alert(data.replace(reCat,"libinqq"));

    6）split   利用正则分割数组

       var data = "123123,213,12312,312,3,Cat,cat,dsfsdfs,";
       var reCat = /\,/;
       var arrdata = data.split(reCat);

       for (var i = 0; i < arrdata.length; i++)
       {
            alert(arrdata);
       }

3  学习下  简单类   负向类  范围类  组合类

    //简单类
       var data = "1libinqq,2libinqq,3libinqq,4libinqq";
       var reCat = /[123]libinqq/gi;
       var arrdata = data.match(reCat);

       for (var i = 0; i < arrdata.length; i++)
       {
            alert(arrdata);  // 1libinqq 2libinqq  3libinqq
       }

       //负向类
       var data = "alibinqq,1libinqq,2libinqq,3libinqq,4libinqq";  //\u0062cf
       var reCat = /[^a123]libinqq/gi;
       var arrdata = data.match(reCat);

       for (var i = 0; i < arrdata.length; i++)
       {
            alert(arrdata);  //4libinqq
       }

       //范围类
       var data = "libinqq1,libinqq2,libinqq3,libinqq4,libinqq5";  //\u0062cf
       var reCat = /libinqq[2-3]/gi;
       var arrdata = data.match(reCat);

       for (var i = 0; i < arrdata.length; i++)
       {
            alert(arrdata);   // libinqq2  libinqq3
       }

       //组合类
      var data = "a,b,c,w,1,2,3,5";  //\u0062cf
       var reCat = /[a-q1-4\n]/gi;
       var arrdata = data.match(reCat);

       for (var i = 0; i < arrdata.length; i++)
       {
            alert(arrdata);  // a b c 1 2 3
       }
二  javascript  正则表达式是分组知识
1） 简单分组

    <script language="JavaScript">  
      <!--  
            
          
        var data = "Ah-mousemouse";    
        var reCat = /(mouse){2}/gi;     
        var arrdata = data.match(reCat);  
     
        for (var i = 0; i < arrdata.length; i++)  
        {  
            alert(arrdata[i]);  
        }  
      //-->  
      </script> 

2 复杂分组
    <script language="JavaScript">  
      <!--  
            
          
        var data = "bb ba da bad dad aa ";    
        var reCat = /([bd]ad?)/gi;   // 匹配出 ba da bad  dad  
        var arrdata = data.match(reCat);  
     
        for (var i = 0; i < arrdata.length; i++)  
        {  
            alert(arrdata[i]);  
        }      
          
     
        // 同时 也不介意将分组放在分组中间  
        // var re = /(mom( and dad)?)/;    匹配出 mom  或  mon and daa  
      //-->  
      </script> 

3 反向引用
    <script language="JavaScript">  
      <!--  
         
     
        var sToMatch = "#123456789";  
        var reNumbers = /#(\d+)/;  
        reNumbers.test(sToMatch);  
        alert(RegExp.$1);  
     
         
     
     
        var sToChange = "1234 5678";  
        var reMatch = /(\d{4}) (\d{4})/;  
        var sNew = sToChange.replace(reMatch,"$2 $1");  
        alert(sNew);  
     
         
     
      //-->  
      </script> 

4 候选
    <script language="JavaScript">  
      <!--  
         
        var sToMatch1 = "red";  
        var sToMatch2 = "black";  
        var reRed = /red/;  
        var reBlack = /black/;  
     
        alert(reRed.test(sToMatch1) || reBlack.test(sToMatch1));  
        alert(reRed.test(sToMatch2) || reBlack.test(sToMatch2));  
     
         
     
        var sToMatch1 = "red";  
        var sToMatch2 = "black";  
        var reRedOrBlack = /(red|black)/;  
        alert(reRedOrBlack.test(sToMatch1));  
        alert(reRedOrBlack.test(sToMatch2));  
     
      //-->  
      </script> 

5 非捕获性分组
    <script language="JavaScript">  
      <!--  
         
     
        var sToMatch = "#123456789";  
        var reNumbers = /#(?:\d+)/;  
        reNumbers.test(sToMatch);  
        alert(RegExp.$1);  
     
         
     
        var sToMatch = "#123456789";  
        var reNumbers = /#(?:\d+)/;  
        alert(sToMatch.replace(reNumbers,"abcd$1"));  
     
         
      //-->  
      </script> 

6 前瞻
    <script language="JavaScript">  
      <!--  
         
     
     
          var sToMatch1 = "bedroom";  
          var sToMatch2 = "bedding";  
          var reBed = /bed(?=room)/;   
          alert(reBed.test(sToMatch1));  //true  
          alert(reBed.test(sToMatch2));  //false  
         
        //负向前瞻  
          
          var sToMatch1 = "bedroom";  
          var sToMatch2 = "bedding";  
          var reBed = /bed(?!room)/;   
          alert(reBed.test(sToMatch1)); //false  
          alert(reBed.test(sToMatch2)); //true  
      //-->  
      </script> 

7 边界
    <script language="JavaScript">  
      <!--  
         
     
          var sToMatch = "Important word is the last one.";  
          var reLastWord = /(\w+)\.$/;   
          reLastWord.test(sToMatch);  
          alert(RegExp.$1);  //one  
     
         
     
     
     
          var sToMatch = "Important word is the last one.";  
          var reLastWord = /^(\w+)/;   
          reLastWord.test(sToMatch);  
          alert(RegExp.$1);  //Important  
     
         
         
          var sToMatch = "Important word is the last one.";  
          var reLastWord = /^(.+?)\b/;   
          reLastWord.test(sToMatch);  
          alert(RegExp.$1);  //Important  
          
         
     
        var data = " First second thind fourth fifth sixth ";    
        var reCat = /\b(\S+?)\b/g;     
        var arrdata = data.match(reCat);  
     
        for (var i = 0; i < arrdata.length; i++)  
        {  
            alert(arrdata[i]);  
        }     
     
         
      //-->  
      </script> 

8 多行模式
    <script language="JavaScript">  
      <!--  
            
          
        var data = " First second\n thind fourth\n fifth sixth";    
        var reCat = /(\w+)$/g;     
        var arrdata = data.match(reCat);  
     
        for (var i = 0; i < arrdata.length; i++)  
        {  
            alert(arrdata[i]);  
        }    
          
            
        var data = " First second\n thind fourth\n fifth sixth";    
        var reCat = /(\w+)$/gm;     
        var arrdata = data.match(reCat);  
     
        for (var i = 0; i < arrdata.length; i++)  
     
        {  
            alert(arrdata[i]);  
        }  a  
          
     
      //-->  
      </script>