The implementation code of the bank card number automatically inserts the space every 4 bits based on the jquery implementation _jquery

The difficulty is not to insert a space, but to correct the position of the cursor, which only supports ie9+, Chrome browser

Note: This uses the jquery framework

Core code

$ (function () {

      $ (' #kahao '). On (' KeyUp ', function (e) {
       ///only when entering numbers)
        if (E.which >= && E.which <=) | |
            (E.which >= && E.which <= 105)) {
          //Get the position of the current cursor
          var caret = This.selectionstart
          //Get the current value
          var value = This.value
          // The number of spaces from the left to the coordinates
          var sp = (Value.slice (0, caret). Match (/\s/g) | | []). Length
          //Remove all spaces
          var nospace = value.replace (/\s/g, ')
          //re-insert space
          var curval = This.value = Nospace.replace (/(\d{4})/g, "$".
          the number of spaces from the left along to the original coordinates
          var cursp = (Curval.slice (0, caret). Match (/\s/g ) || []). length
         //fixed cursor position
         this.selectionend = This.selectionstart = caret + cursp-sp
        
        }
      }
    )

Full code: already tested

<! 
  DOCTYPE html>  

The test was really good, and it used a lot of regular

\s matches any white space character, including spaces, tabs, page breaks, and so on. equivalent to [\f\n\r\t\v].

For a tutorial on regular expressions, refer to this article:

Http://www.jb51.net/tools/zhengze.html

Http://www.jb51.net/tools/regexsc.htm