how can I count number of digits with leading zeros in javascript?

I have a form where a user enters a number, say an employee ID number or something like that. The field is set to reject anything that's not a number, so they can't just put in "bob" or faceroll the keyboard or whatever. Otherwise I'd convert this to a string.

I need to further validate and make this form reject anything that doesn't match the correct number of digits, lets say 5. It also needs to count leading zeros. For example - let's assume an Employee ID of 01234, which should match 5 digits. Currently, I'm losing that leading zero and it's rejecting values like the example above.

So, how can I:

  • count the number of digits in this number,
  • preserve leading zeros,
  • make sure they user is obligated to enter a number, with a JavaScript formula?

You should go with your original idea and use a string for such a field. You can check whether the string is a number with a simple regex such as

let regex = /^[0-9]*$/;

It should return true if the string contains only digits.

javascript print int with leading zeros Code Example, Get code examples like "javascript print int with leading zeros" instantly right javascrript format number with leading zeros � left zero javascript count duplicates array js � count number of checkboxes in html jquery � Count� See the Pen JavaScript - Get the day of the month, 2 digits with leading zeros-date-ex-19 by w3resource (@w3resource) on CodePen. Improve this sample solution and post your code through Disqus. Previous: Write a JavaScript program to calculate age. Next: Write a JavaScript function to get a textual representation of a day (three letters, Mon

If you get the input element's value with element.value it will return a string that preserves leading zeroes.

Limiting the input field's characters is covered in HTML text input allow only numeric input

I've copied and modified the example below to show an input field that only accepts up to 8 numbers and will log the ID on submit.

// Restricts input for the given textbox to the given inputFilter.
// Source:
function setInputFilter(textbox, inputFilter) {
  ["input", "keydown", "keyup", "mousedown", "mouseup", "select", "contextmenu", "drop"].forEach(function(event) {
    textbox.addEventListener(event, function() {
      if (inputFilter(this.value)) {
        this.oldValue = this.value;
        this.oldSelectionStart = this.selectionStart;
        this.oldSelectionEnd = this.selectionEnd;
      } else if (this.hasOwnProperty("oldValue")) {
        this.value = this.oldValue;
        this.setSelectionRange(this.oldSelectionStart, this.oldSelectionEnd);

const inputField = document.getElementById("employee-id");
const submitButton = document.getElementById("submit");

setInputFilter(inputField, function(value) {
  return /^\d*$/.test(value) && (value.length <= 8);;
submitButton.addEventListener('click', event => {
User ID: <input id="employee-id">
<button id="submit">submit</button>

Simplest way for leading zero padding in JavaScript � GitHub, You have bug with negative numbers. Number.prototype.pad = function(size) { var sign = Math.sign(this) === -1 ? '-' : ''; return sign + new� If you wanted to add zeros to a number in cell B3 so that the total number of digits is 6, then you can use the above formula. RIGHT Function. Another way to get your zeros in front with a formula is using the RIGHT function. You can concatenate a string of zeros to the number and then slice off the extras using the RIGHT function.

Try this.

<input id="number" type="text" minlength="5" maxlength="5" value="42" pattern="\d{5}">

Check validity via JS


check validity via CSS

input {
  outline: none;
  border: 1px solid green;
input:invalid {
  border: 1px solid red;

if you need further validation just use javascript to validate it.

Format a number with leading zeros in PHP, How to remove all leading zeros in a string in PHP ? How to format current date in MM/DD/YYYY HH:MM:SS format using JavaScript ? Golang Program to Count � I have a form where a user enters a number, say an employee ID number or something like that. The field is set to reject anything that's not a number, so they can't just put in "bob" or faceroll the

Remove leading zeros from a Number given as a string , Count of N-bit binary numbers without leading zeros � All possible numbers of N digits and base B without leading zeros � Number of ways to remove a sub-string � So, B ‘N’ digit numbers are possible with base ‘B’ (including the numbers with leading zeros). And, if we fix the first digit as ‘0’ then the rest of the ‘N-1’ digits can form a total of B numbers. So, total number of ‘N’ digit numbers with base ‘B’ possible without leading zeros are B – B.

Pad a number with leading zeroes in Javascript, Please note: this doesn't work for negative numbers; it was designed specifically for padding with leading a zeros a number which will be used in date formats� Today, I have a little tip showing how you can remove all leading zeros from a string in JavaScript: var s = '00123'; var i = Number(s); alert(i); // '123' Number() converts the parameter passed into a number. Because numbers are not containing leading zeros, the zeros from the beginning of our string are dropped out automatically.

JavaScript basic: Find the number of trailing zeros in the decimal , Write a JavaScript program to find the number of trailing zeros in the a number from three given numbers where two numbers are equal, find the third one. Next: Write a JavaScript program to calculate the sum n + n/2 + n/4 +� Format a number with leading zeros in PHP Often times, while writing a code we face situations where we need to pad a numbers/strings and make them of a default length. In this article, we will learn how to pad a number with leading zeros in PHP.

  • We need to see your code and what you've tried
  • store the "number" as a string, then just use .lenght
  • Nice Answer, you should update the answer though to complete it. I.e, if it is true, then calculate the length of the string with regex = regex.split(""), let length = regex.length for example :)