counter with multiple digits

I'm fairly new to Javascript and have been able to get by so far by just following tutorials and reading forums but this one really stumped me for a while.

Basically I wanted to have 开发者_如何学Ca counter for numbers that contain seven digits, I found a few things but none that really made sense to me so I wrote this:

imgNumber++;
if (imgNumber < 10){function add(number){return '00000' + number}};
if (imgNumber > 10 && imgNumber < 100){function add(number){return '0000' + number}};
if (imgNumber > 100 && imgNumber < 1000){function add(number){return '000' + number}};
if (imgNumber > 1000 && imgNumber < 10000){function add(number){return '00' + number}};
if (imgNumber > 10000 && imgNumber < 100000){function add(number){return '0' + number}};
if (imgNumber > 100000 && imgNumber < 1000000){function add(number){return '' + number}};

It works as far as I can tell. My question is this: Do you foresee any issues with this and if not is there a cleaner way to write all this?

I'll appreciate any and all replys.

Cheers, Colin

As with all programming functions are your friend. I searched google for padding zeros javascript and got directed to this site.

function pad(number, length) {
       var negative = number < 0;
       var str = '' + Math.abs(number);
       while (str.length < length) {
           str = '0' + str;
       }
       if(negative) str = '-' + str;
    return str;
}

Using this you would just generate your number standard and prior to storing/outputting it you'd run it through this function:

pad(1,7);

A one liner:

var output = sprintf("%07d", 30);

Believe me, it will save you a lot of time in javascript (and in other languages). You can download the implementation in http://sprintf.googlecode.com/files/sprintf-0.7-beta1.js

By today, this code works right now, perhaps you need to change the src of the library for a more updated:

<script type="text/javascript" src="http://sprintf.googlecode.com/files/sprintf-0.7-beta1.js"> </script>

<script type="text/javascript" >
   alert(sprintf("%04d",4));
</script>

More information, here, plus there are other implementations of this useful method.

Why don't you just take the log (base 10) of the number as an indicator of how many digits to add.

If log(N) is between 0 and less than 1, N is a one digit number.
If log(N) is greater than or equal to 1 but less than 2, N has two digits, and so forth.

I don't actually code in JavaScript, so I don't know if you have access to a log function, but if you do, this is a very terse way to get the result.

John Doner