How could I request a certain number (digit) with a certain times to be inserted in an input element?

问题

How could I request a certain digit with a certain times to be inserted in an input element?

I need to request from The users to input three times a certain digit, let we say number 9, in the text or password field, in any format..

How could I do that using HTML5 or any other way?

If I had this code:

<td><input type="password" name="password" maxlength="9" pattern="\d+" title="9 numbers only" placeholder="9 numbers only"  value="<?php echo htmlentities($password); ?>" /></td>

Then, my required pattern to be as example: ("x" is any digit)

xxx999xxx

Or: x9x9x9xxx

Or: 9xxx9xxx9

Or: x9xxxx99x

It doesn't matter the format, the matter is 3 times of number 9 to be inserted every time.

回答1:

You can use this tool for Regular Expressions: http://gskinner.com/RegExr/.

This pattern should work: [^9.]*9[^9.]*9[^9.]*9[^9.]*

回答2:

You can get the frequecy of the character in javascript like

    <script language="javascript" type="text/javascript">

        alert ('hi');
        var arr="sandeeep".split('');
        var uniqs = {};

        for(var i = 0; i < arr.length; i++) {
            uniqs[arr[i]] = (uniqs[arr[i]] || 0) + 1;
        }
         var countarr = { val: arr[0], count: 1 };
        for(var u in uniqs) {
            if(countarr.count < uniqs[u]) { countarr= { val: u, count: uniqs[u] }; }
        }
        alert( countarr.count);
    </script>

from the above code