NOTE: Potentially outdated. ECMAScript 2017 includes
String.prototype.padStart.
You'll have to convert the number to a string since numbers don't make sense with leading zeros. Something like this:
function pad(num, size) {
num = num.toString();
while (num.length < size) num = "0" + num;
return num;
}
Or, if you know you'd never be using more than X number of zeros, this might be better. This assumes you'd never want more than 10 digits.
function pad(num, size) {
var s = "000000000" + num;
return s.substr(s.length-size);
}
If you care about negative numbers you'll have to strip the - and re-add it.
Top answer 1 of 6
989
NOTE: Potentially outdated. ECMAScript 2017 includes
String.prototype.padStart.
You'll have to convert the number to a string since numbers don't make sense with leading zeros. Something like this:
function pad(num, size) {
num = num.toString();
while (num.length < size) num = "0" + num;
return num;
}
Or, if you know you'd never be using more than X number of zeros, this might be better. This assumes you'd never want more than 10 digits.
function pad(num, size) {
var s = "000000000" + num;
return s.substr(s.length-size);
}
If you care about negative numbers you'll have to strip the - and re-add it.
2 of 6
690
UPDATE: Small one-liner function using the ES2017 String.prototype.padStart method:
const zeroPad = (num, places) => String(num).padStart(places, '0')
console.log(zeroPad(5, 2)); // "05"
console.log(zeroPad(5, 4)); // "0005"
console.log(zeroPad(5, 6)); // "000005"
console.log(zeroPad(1234, 2)); // "1234"Another ES5 approach:
function zeroPad(num, places) {
var zero = places - num.toString().length + 1;
return Array(+(zero > 0 && zero)).join("0") + num;
}
zeroPad(5, 2); // "05"
zeroPad(5, 4); // "0005"
zeroPad(5, 6); // "000005"
zeroPad(1234, 2); // "1234" :)
Medium
hardiquedasore.medium.com › simplest-way-to-add-a-leading-zero-to-a-number-in-javascript-b8724749486f
Simplest way to add a leading zero to a number in Javascript | by Hardique Dasore | Medium
August 27, 2021 - In this method, we add a zero to the number and slice to extract 2 digit value of the result. We use negative value to select from end of the string. const number = 9;console.log(("0" + number).slice(-2))//Output: 09 ... const number = 9;if(number< ...
Codedamn
codedamn.com › news › javascript
How to add leading zero to a number in JavaScript
February 19, 2024 - Numeral.js employs a format string mechanism, where ‘0’ represents a digit placeholder that will be replaced with the corresponding digit from the number, ensuring leading zeros are included as needed. Real-world use cases for adding leading zeros in JavaScript, with detailed examples.
Reddit
reddit.com › r/learnjavascript › leading zeros in number, what's going on here?
r/learnjavascript on Reddit: Leading zeros in number, what's going on here?
September 4, 2022 -
So I have created a WPF program in C# which I wanted to port to JS and have it web based. However numbers seem to behave quite differently in JS. Can someone tell me what's this "compiler" is doing?
I know I can create a ASP/webforms app to do this, but just wanted to dive into another language.
Top answer 1 of 3
6
That's because these numbers are in octal representation : 000023 = 23 (octal) = 2 * 81 + 3 * 80 = 16 + 3 = 19 (decimal) https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Numbers_and_dates#decimal_numbers Note that decimal literals can start with a zero (0) followed by another decimal digit, but if every digit after the leading 0 is smaller than 8, the number gets parsed as an octal number. Also : https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Numbers_and_dates#octal_numbers Strict mode forbids this octal syntax.
2 of 3
1
It is becouse you named variable "fuckYouJS". JavaScript went mad, bro! Super mad! 😀
TutorialsPoint
tutorialspoint.com › how-to-pad-a-number-with-leading-zeros-in-javascript
How to pad a number with leading zeros in JavaScript?
In JavaScript, the String object's padStart() method is useful to pad a number with leading zeros. It takes two parameters, the first one is the total length of the targeted or desired string, and the other one is the string or character the user wants to use for padding.
Edureka Community
edureka.co › home › community › categories › web development › java-script › how can numbers be formatted with leading zeros...
How can numbers be formatted with leading zeros in JavaScript | Edureka Community
298742/how-can-numbers-be-formatted-with-leading-zeros-javascript
GitHub
gist.github.com › endel › 321925f6cafa25bbfbde
Simplest way for leading zero padding in JavaScript · GitHub
Number.prototype.pad = function(size) { var s = String(this); var getsize = ()=>{ var j = 0, fc = false; for(var i=0; i<s.length; i++){ if(!fc){if(s.charAt(i) == '.'){ fc = true; }else{ j++; }}} return j; }; //console.log(getsize()); while (getsize() < (size || 2)) {s = "0" + s;} return s; }
GitHub
gist.github.com › 2584764
JavaScript: format number with leading zero · GitHub
JavaScript: format number with leading zero. GitHub Gist: instantly share code, notes, and snippets.
MDN Web Docs
developer.mozilla.org › en-US › docs › Web › JavaScript › Reference › Global_Objects › String › padStart
String.prototype.padStart() - JavaScript | MDN
// JavaScript version of: (unsigned) // printf "%0*d" width num function leftFillNum(num, targetLength) { return num.toString().padStart(targetLength, "0"); } const num = 123; console.log(leftFillNum(num, 5)); // "00123"
Codemia
codemia.io › knowledge-hub › path › how_to_output_numbers_with_leading_zeros_in_javascript
How to output numbers with leading zeros in JavaScript?
Enhance your system design skills with over 120 practice problems, detailed solutions, and hands-on exercises
Bobby Hadz
bobbyhadz.com › blog › javascript-add-leading-zeros-to-number
How to add Leading Zeros to a Number in JavaScript | bobbyhadz
The padWithLeadingZeros() function takes a number and its desired total length as parameters and pads the number with leading zeros if necessary.
Rafaelcamargo
rafaelcamargo.com › blog › handling-leading-zeros-with-javascript
Handling leading zeros with JavaScript
If I define a CEP as 89203-85, ... the code to have 5 digits followed by another 3, separated by a hyphen. To make the CEP valid, it is necessary to add a leading zero to the number 85: 89203-085....
Delft Stack
delftstack.com › home › howto › javascript › javascript leading zeros
How to Append Leading Zeros in JavaScript | Delft Stack
February 2, 2024 - To deal with negative numbers, we had to remove the minus sign, add the leading zeros, and add the minus sign to the beginning of the string.
Top answer 1 of 15
2
function pad(toPad, padChar, length){
return (String(toPad).length < length)
? new Array(length - String(toPad).length + 1).join(padChar) + String(toPad)
: toPad;
}
pad(5, 0, 6) = 000005
pad('10', 0, 2) = 10 // don't pad if not necessary
pad('S', 'O', 2) = SO
...etc.
Cheers
2 of 15
2
Just for fun, here's my version of a pad function:
function pad(num, len) {
return Array(len + 1 - num.toString().length).join('0') + num;
}
It also won't truncate numbers longer than the padding length
DEV Community
dev.to › hardiquedasore › simplest-way-to-add-a-leading-zero-to-a-number-in-javascript-1nne
Simplest way to add a leading zero to a number in Javascript - DEV Community
November 18, 2022 - 1.slice() method In this method, we add a zero to the number and slice to extract 2 digit value of the result. We use negative value to select from end of the string. const number = 9; console.log(("0" + number).slice(-2)) //Output: 09 ... const ...
Linux Hint
linuxhint.com › output-numbers-with-leading-zeros-in-javascript
How to Output Numbers With Leading Zeros in JavaScript
Linux Hint LLC, [email protected] 1210 Kelly Park Circle, Morgan Hill, CA 95037 Privacy Policy and Terms of Use
Byby
byby.dev › js-number-leading-zeros
How to add zeros before number in javascript
Finally, it adds the leading zeros using a loop and returns the resulting string. Number.prototype.pad = function (n) { let numString = this.toString(); let zerosToAdd = n - numString.length; for (let i = 0; i < zerosToAdd; i++) { numString = "0" + numString; } return numString; }; const num = 4; console.log(num.pad(4)); //=> "0004"
The Valley of Code
thevalleyofcode.com › js-add-leading-zero
How to add leading zero to a number in JavaScript
I had the need to add a leading zero when the number I had was less than 10, so instead of printing “9” on the screen, I had “09”.
Latenode
community.latenode.com › other questions › javascript
Format date with leading zeros in JavaScript - JavaScript - Latenode Official Community
October 12, 2024 - I have a script that calculates a date 10 days from now and formats it as dd/mm/yyyy. var currentDate = new Date(); var formattedDate = new Date(); currentDate.setDate(currentDate.getDate() + 10); formattedDate = currentDate.getDate() + '/' + (currentDate.getMonth() + 1) + '/' + currentDat...
30 Seconds of Code
30secondsofcode.org › home › javascript › number › number formatting
Formatting numeric values in JavaScript - 30 seconds of code
February 14, 2024 - Last but not least, you might need to pad a number with leading zeros to a specific length. We can use String.prototype.padStart() to pad the number to the specified length, after converting it to a string. const padNumber = (n, l) => `${n}`.padStart(l, '0'); padNumber(1_234, 6); // '001234' ... An ES6 article collection for formatting and manipulating dates with native JavaScript.