1.通过js原生方法实现:

1. <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">  
2. <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">  
3. <head>  
4. <meta http-equiv="Content-Type" content="text/html;charset=UTF-8">  
5. <title>Document</title>  
6. <script src="js/jQuery.js"></script>  
7. </head>  
8. <body>  
9. <script>  
10. num = 0;  
11.     function inputAccount(){  
12.         
13. str = $('#bankCard').val();  
14.         
15. elem = document.getElementById("bankCard");  
16.         
17.       console.log(elem);  
18.         
19. > num){  
20. c = str.replace(/\s/g,  "");   
21.             
22. > 4 && c.length % 4 == 1){  
23.             $('#bankCard').val(str.substring(0, str.length - 1)+ " " + str.substring(str.length - 1, str.length));  
24.                 
25.           }  
26.       }  
27.         
28.       if(elem.setSelectionRange){//W3C  
29.             setTimeout(function(){  
30.                 elem.setSelectionRange(elem.value.length,elem.value.length);  
31.                 elem.focus();  
32.             },0);  
33.         }else if(elem.createTextRange){//IE  
34. textRange=elem.createTextRange();  
35.             textRange.moveStart("character",elem.value.length);  
36.             textRange.moveEnd("character",0);  
37.             textRange.select();  
38.         }  
39.         
40. num = str.length;  
41.         
42.   }  
43.   
44. </script>  
45.   
46.   
47. <input type="text" name="" oninput="inputAccount()" id="bankCard" />  
48. </body>  
49. </html>

2.通过jQuery实现:

    1. <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">  
    2. <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">  
    3. <head>  
    4. <meta http-equiv="Content-Type" content="text/html;charset=UTF-8">  
    5. <title>Document</title>  
    6. <script src="js/jQuery.js"></script>  
    7. </head>  
    8. <body>  
    9.       
    10.   
    11.   
    12. <input type="text" name="" id="box" />  
    13. <script>  
    14.       $(function(){  
    15.         $('#box').keyup(function(){  
    16. value=$(this).val().replace(/\s/g,'').replace(/(\d{4})(?=\d)/g,"$1 ");    
    17.           $(this).val(value)  
    18.         })   
    19.       })   
    20. </script>  
    21. </body>  
    22. </html>  
    23. 第