adding zeros in front of a string

Question

I need your help.

I'd like to create a function that would add some zeros in front of a number. The maximum numbers of digits that the total string should have is 6. Here are examples:

     9 -> 000009
    14 -> 000014
   230 -> 000230
  1459 -> 001459
 21055 -> 021055
987632 -> 987632 (Do nothing, there's already 6 digits)

Good luck! Let us know when you've tried something and have some specific bug you need help with. — Blazemonger, May 27 '15 at 19:01
possible duplicate of [How can I create a Zerofilled value using JavaScript?](http://stackoverflow.com/questions/1267283/how-can-i-create-a-zerofilled-value-using-javascript) — MasterAM, Jun 23 '15 at 20:58

score 13 · Answer 1 · answered May 27 '15 at 19:53

13

A simple one line solution without any loops

Works with IE5-11, Firefox, Chrome, etc. Assumes integer input.

 function pad(n) { return ("000000" + n).slice(-6); }

Run snippet to test:

<html>
<body>
<input id="stdin" placeholder="enter a number" maxlength="6"><button onclick="test()">Test</button>
<textarea id="stdout" style="width:100%;height:20em;padding:1em;"></textarea>
<script type="text/javascript">
    
   function pad(n) { return ("000000" + n).slice(-6); }
    
   function test() {
       var n = parseInt( document.getElementById('stdin').value);
       var e = document.getElementById('stdout').innerHTML += n + ' = ' + pad(n) + '\n';
   }
 
</script>
</body>
</html>

answered May 27 '15 at 19:53

Yogi

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2

And if you want to be able to define the length of padding dynamically: `function pad(n, len) { return ((new Array(len + 1).join('0')) + n).slice(-len); }` – gfullam May 27 '15 at 20:43
2

A significantly more performant way to allow for dynamically declaring length: `function pad(n, str) { return (str + n).slice(-str.length); }` **Usage:** `pad(number, '000000');` By passing a static string you get the [performance boost (JSPerf)](http://jsperf.com/adding-zeros-in-front-of-a-string/4) from not dynamically creating the string on each invocation. **Bonus:** You get the added benefit of being able to pass in any string: `pad(number, '######');` – gfullam May 29 '15 at 14:14

score 5 · Answer 2 · answered May 27 '15 at 19:04

5

The following will add a zero to the string of numbers until the length is equal to 6.

var s = '9876'
while(s.length < 6){
  s = '0' + s
}
alert(s)

answered May 27 '15 at 19:04

Woodsy

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talemyn · Answer 3 · 2015-05-27T19:59:38.500

One more . . . this one works with:

strings and numbers,
handles variable lengths, and
lets you chose the padding character

Code:

function padZerosToLength (value, minLength, padChar) {
    var iValLength= value.toString().length;
    return ((new Array((minLength + 1) - iValLength).join(padChar)) + value);
}

Here are some sample results with varying input:

padZerosToLength(1, 6, 0);       ===>  000001
padZerosToLength(12, 6, 0);      ===>  000012
padZerosToLength(123, 6, 0);     ===>  000123
padZerosToLength(1234, 6, 0);    ===>  001234
padZerosToLength(12345, 6, 0);   ===>  012345
padZerosToLength(123456, 6, 0);  ===>  123456

. . . with varying length:

padZerosToLength(1, 1, 0);  ===>  1
padZerosToLength(1, 2, 0);  ===>  01
padZerosToLength(1, 3, 0);  ===>  001
padZerosToLength(1, 4, 0);  ===>  0001
padZerosToLength(1, 5, 0);  ===>  00001
padZerosToLength(1, 6, 0);  ===>  000001

. . . and with varying padding character:

padZerosToLength(1, 6, 0);         ===>  000001
padZerosToLength(1, 6, 1);         ===>  111111
padZerosToLength(1, 6, "x");       ===>  xxxxx1
padZerosToLength(1, 6, ".");       ===>  .....1
padZerosToLength(1, 6, " ");       ===>       1
padZerosToLength(1, 6, "\u25CF");  ===>  ●●●●●1

score 1 · Answer 4 · answered May 27 '15 at 19:09

You will need to convert the number to a string. Then I would split that string to an array and then add '0' to the front of that array until the length is 6. Then join. Check out this repl or see the code below: http://repl.it/piT

var num = 14;
var lengthOfNum = 6;
var numString = num.toString();
var numArray = numString.split('');
var returnString = '';

while (numArray.length < 6) {
    numArray.unshift('0');
}

returnString = numArray.join('');

score 0 · Answer 5 · answered May 27 '15 at 19:09

0

Recursive solution just for the heck of it:

function padNumberString(numberString) {
    if (numberString.length >= 6) {
        return numberString;
    }
    return padNumberString('0' + numberString);
}

answered May 27 '15 at 19:09

thewatcheruatu

242
2
9

score 0 · Answer 6 · answered Sep 02 '22 at 06:54

0

String.prototype.padStart()

padStart(targetLength)
padStart(targetLength, padString)
'123'.padStart(5, "0");     // "00123"

For more detail you could look at developer.mozilla --> String.prototype.padStart()

answered Sep 02 '22 at 06:54

husnu

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GANI · Answer 7 · 2015-05-29T19:17:04.817

-1

A simple solution would be

    function addLeadingZeros (n, length)
    {
     var str = (n > 0 ? n : -n) + "";
     var zeros = "";
      for (var i = length - str.length; i > 0; i--)
         zeros += "0";
     zeros += str;
    return n >= 0 ? zeros : "-" + zeros;
    }

//addLeadingZeros (9, 3) =   "009"
//addLeadingZeros (15, 3) =  "015"
//addLeadingZeros (333, 3) = "333"

edited May 29 '15 at 19:17

answered May 27 '15 at 21:09

GANI

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Is this Java? This question is tagged `JavaScript`. – Evan Davis May 29 '15 at 17:18
1

man..I didnt see this, am selected .net tag this question qppeared – GANI May 29 '15 at 19:13

score -2 · Answer 8 · answered May 27 '15 at 19:02

-2

I have been using the SugarJs API for a long time and their padding feature works great.

http://sugarjs.com/api/Number/pad

(9).pad(6, true) --> 000009
(14).pad(6, true) --> 000014

etc...

answered May 27 '15 at 19:02

beauXjames

8,222
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adding zeros in front of a string

8 Answers8

A simple one line solution without any loops

Linked