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I want to create a script function which will validate if the user input contains more than one decimal i.e 2.434 should be the correct number but if the user tries to input a NUMBER LIKE 2.4.5.6 it will not take the input in the field. It will take only number after a decimal point but not another single decimal point. no 2.2.2. but 2.2222. Will use it in a .net page.
tried different patterns like ^-{0,1}\d+.{0,1}\d*$ but could not get result. added the function i am already using. need to add the decimal part in the given code.
function isNumberKey(evt) {
var first;
var charCode = (evt.which) ? evt.which : evt.keyCode;
if (charCode == 46) {
return true;
}
if (charCode == 46 || charCode > 31 && (charCode < 48 ||
charCode > 57))
return false;
return true;
}
text box will take input when 2.22 or 3.455654 but won't take 2.3.34.4. when the user writes something like this the cursor won't change the position or take the input number.
The code provided does not validate the entire string. It just checks that the key pressed is a digit, which does not help much. There are many ways to do what you want:
1- Browser validation using type="number":
You can use an input with type "number"; then the browser will do a validation on its own before the form submits (this also accepts integers though):
<input type="number" name="decimal" />
2- Browser validation using the patternattribute:
A handy property you can set for inputs is the pattern attribute. You can set it to the desired regex, and the browser will make sure the user's input matches the regex before submitting the form.
<input type="text" name="decimal" pattern="^-?\d+\.?\d*$" />
3- Custom validation with Javascript:
This approach definitely gives you more flexibility, and allows you to validate once the user typed the input, instead of validating on form submit.
Assuming you have a text input, you can listen to the onchange event to validate the entire string, after the user has finished typing their input.
Edit: As for the regular expression, you need to escape the dot, so replace (. by \.). Plus, {0, 1} is equivalent to ?, as pointed out by #CodeManiac in the comments.
var input = document.getElementById("decimal-input");
input.onchange = function() {
var text = this.value;
if(!text.match(/^-?\d+\.?\d*$/)) {
this.value = ""; //clear input
console.log("Please enter a valid decimal.");
}
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<form>
<input type="text" id="decimal-input" placeholder="Enter a decimal..."/>
</form>
in the event target is the reference to the input element. So you are able to obtain the whole string
function isNumberKey(evt) {
s=evt.target.value;
console.log(s);
if (s.length !==0){
arr=s.split(".");
if (arr.length>0){
return false;
}
///... other checks...
}
there might be also a dirty way to check the whole number
try {
x=eval(s*1) ;
} catch (ex){
return false
}
or just do it on the enter key to implement a tiny calculator in your input ;)
Funtion setupField is called with the id of an input field to be initialized with an onkeyup event that will only allow valid input to be entered into the field. The regular expression it uses allows an optional + or - sign. The number itself can be of the format: 123, 123., 123.45, or .45
To allow an initial entry of the +, -, or . characters, the regular expression must also consider these characters to be legal input. When the form is submitted, there is always the possibility that only one of these 3 characters or no characters at all have been entered. It is easy enough to test for a valid decimal number by testing isNan(parseFloat(input)) against the input.
^(([+-]?\d+(\.\d*)?)|[+-]?(\.\d+)|[\+-\.])$
<!doctype html>
<html>
<head>
<meta name=viewport content="width=device-width,initial-scale=1">
<meta charset="utf-8">
<script>
function setupField(field)
{
let re = /^(([+-]?\d+(\.\d*)?)|[+-]?(\.\d+)|[\+-\.])$/;
field.autocomplete = "off";
field.saveValue = field.value;
field.onkeyup = function() {
var v = field.value;
if (v === '' || re.test(v)) {
field.saveValue = v;
}
else {
field.value = field.saveValue;
}
};
field.onchange = function() {
var v = field.value;
if (isNaN(parseFloat(v)))
console.log('You entered invalid input.');
};
}
function init()
{
setupField(document.getElementById('x'));
}
</script>
<body onload="init();">
<input type="input" id="x" size="10">
</body>
</html>
I have textbox in which I need validation in such way that it should not allow spaces if textbox is empty. If any values are there in textbox then only it should allow spaces. I am trying below code but not working
var letters = /^[0-9a-zA-Z]+$/;
$("#input1").on("blur ", function() {
function alphanumeric(username) {
if (username.value.match(letters)) {
return true;
} else {
$('#input1').on('keypress', function(e) {
if (e.which == 32)
return false;
});
return false;
}
}
})
if you are using form, you do not need any javascript
<form action='/'>
<input pattern="\s*\S+.*" title="space only is not allowed" required/>
<input type="submit">
</form>
why not just trim?
username.trim()
after that you can just return the result of match.
Add a function on your blur event that will trim the values which will remove preceding and succeeding whitespace. If the value is empty it will result in '' .
$("#input1").on("blur", function () {
if($(this).val().trim() === ''){
alert('empty value');
}
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input id='input1' />
Your Regex seems wrong.
You're not allowing spaces characters.
Try this one instead: /\S/
\S is any non whitespace character.
If you want to start by a character, it will become /^\S/.
^ is when you want to start by the following character
$ is when you want to finish by the previous character
You can do it like this:
$(function() {
$('#input1').on('keypress', function(e) {
if ($(this).val() == "")
if (e.which == 32)
return false;
});
});
Online Demo (jsFiddle)
I have an input field in which the user should only be able to enter digits [0-9].
document.getElementById("integer").addEventListener('input', restrictToInteger);
function restrictToInteger() {
this.value = this.value.replace(/[^\d]/g, '');
}
<input type="number" id="integer" />
jsFiddle Demo
The problem is this: When I enter a number (eg. 1234) and then press dot (.), + or - the content of the input field is automatically deleted by the browser (value is set to "" = empty string). But why? Changing the type from number to text seems to fix the problem. But then I lose the up/down arrow functionality of the input field. Any ideas?
HTML 4 has an event called onkeypress. With that attribute we can do this without using additional JS:
<input type="number" onkeypress="return (event.charCode == 8 || event.charCode == 0 || event.charCode == 13) ? null : event.charCode >= 48 && event.charCode <= 57">
Here digits from 0 to 9 are allowed using the event.charCode from 48 to 57.
I think the reason that the browser clean the input value it is because a string with two dots it is not a number.
Some corrections about your code:
You need to change your expression regular if you want to accept number with decimal part. Now, you are only express that you want to accept digits [0-9] and no more chars.
To accomplish want you want, you need to change /[^\d]/g to /[^\d.]/g.
document.getElementById("integer").addEventListener('input', restrictToInteger);
function restrictToInteger()
{
this.value = this.value.replace(/[^\d.]/g, '');
}
<input type="number" id="integer" />
HOWEVER: If you define your input as number type, the regular expression is not needed. So, you just need to define the input like this and should your to your case:
<input type="number" id="integer" />
[THE SOLUTION]
To fully meet your needs, I came with a solution that catch the keydown event of the input and check if there is any '.' on the input. If yes, I prevent the char to go to the input.
document.getElementById("integer").addEventListener('keydown', restrictToInteger);
var lastCodeWasDot = false;
function restrictToInteger(e)
{
var inputValue = document.getElementById("integer").value;
var isDot = false;
var isDot = (e.keyCode && e.keyCode == 110) || (e.charCode && e.charCode == 190);
console.log(e.keyCode);
if(isDot && (inputValue.indexOf(".") > -1 || inputValue == "" || lastCodeWasDot)) {
e.preventDefault();
}
lastCodeWasDot = isDot;
}
<input type="number" id="integer" />
Explaning the solution:
The line of code var isDot = (e.keyCode && e.keyCode == 110) || (e.charCode && e.keyCode == 190) || false; is needed because cross browser compatibility.
I don't now why but if you try to get the value from an input number type in the firefox, and if the value finishes with a dot, the value that you will get will be without the last dot of the input. To fix that, I needed to add the variable lastCodeWasDot to fix this issue.
NOTE: The number input can accept floating point numbers, including negative symbols and the e or E character (check out this post)
Based on the answers of Alexandru-Ionut Mihai and natchiketa I created the following solution:
document.getElementById("integer").addEventListener("input", allowOnlyDigits);
function allowOnlyDigits() {
if (this.validity.valid) {
this.setAttribute('current-value', this.value.replace(/[^\d]/g, ""));
}
this.value = this.getAttribute('current-value');
}
<input type="number" id="integer" />
On input the value is checked for validity. If it is valid, all non-digits are removed and the value is stored in a custom attribute of the element. If the value is not valid, the previous value is restored.
Notes:
The RegEx-replace is required only for Internet Explorer as it allows you to enter , or . at the end of a number.
Tested in IE, Edge, Chrome and Firefox
Chrome still allows you to enter a + before and one , after the number.
I found one issue: If you initialize the field with a value, the value is lost when you first hit an invalid char on the keyboard.
Another issue: You can't enter a negative number.
The only problem was your input type. Change it to text and it should work !
function validate(e) {
var charCode = e.keyCode? e.keyCode : e.charCode
if (!(charCode >= 48 && charCode <= 57)) {
if(!(charCode>=37 && charCode<=40))
if(charCode!=8 && charCode!=46)
return false;
}
}
<input type="number" id="integer" pattern="[0-9]"
onkeydown="return validate(event)"/>
You can achieve your requirement by copying the old value of input and using setAttribute and getAttribute methods in order to store the values.
function myFunction(input){
input.setAttribute('current-value',"");
input.oninput=function(){
let currentValue=input.getAttribute('current-value');
if(input.value!='' || (currentValue>=1 && currentValue<=9))
input.setAttribute('current-value',input.value);
input.value=input.getAttribute('current-value');
}
}
<input type="number" oninput="myFunction(this)"/>
<input type="number" oninput="myFunction(this)"/>
<input type="number" oninput="myFunction(this)"/>
<input type="number" oninput="myFunction(this)"/>
<input type="number" oninput="myFunction(this)"/>
When you call oninput, the <input> element first calls its internal methods to handle the value. This prevents your function from seeing any actual erroneous characters, namely e+-. - all used by JavaScript to format numbers.
You can see this by adding console.log calls before and after changing this.value.
console.log(this.value);
this.value=this.value.replace(/[^\d]/g, '');
console.log(this.value);
There is never any difference!
If you try, for example:
console.log(this.value);
this.value+=1; // or *=2 for numerical fun
console.log(this.value);
you can see a difference.
So your function is hastening the normal internal calls <input type='number'/> would normally make when handling illegal input.
Can't quite see why the field is left blank and not 1 though.
I would switch to a cancelable event like keydown.
That way you can prevent the character from being typed in the first place:
var cancelEvent = function (e) {
e.preventDefault();
return false;
},
restrictToInteger = function restrictToInteger(e) {
var acceptableInput = /[0-9]/g,
clipboardKeys = /[zxcv]/ig,
field = e.key || e.char,
isClipboardOperation = (clipboardKeys.test(field) && e.ctrlKey),
inputIsAcceptable = field ? (
acceptableInput.test(field)
|| field.length > 1
|| isClipboardOperation
) : true;
if (!inputIsAcceptable) {
cancelEvent(e);
}
},
ensureIntegerValueOnPaste = function ensureIntegerValueOnPaste(e) {
var data = e.clipboardData || e.dataTransfer,
text = data.getData('text'),
int = parseInt(this.value + text, 10);
if (isNaN(int)) {
cancelEvent(e);
} else {
window.setTimeout(function () {
e.target.value = int;
}, 0);
}
},
input = document.getElementById("integer");
input.addEventListener('keydown', restrictToInteger);
input.addEventListener('drop', ensureIntegerValueOnPaste);
input.addEventListener('paste', ensureIntegerValueOnPaste);
<input type="number" id="integer" />
Updated fiddle: https://jsfiddle.net/838pa8hv/2/
Disclaimers:
Only tested in Chrome.
The test for field.length > 1 is to catch non-numeric keys that are valid as the up/down arrows have a value of ArrowUp and ArrowDown respectively. This also allows for keys like Shift (or Home, Backspace, Delete, etc.) to be pressed as well.
Edit:
To handle pastes (and drops), you can do the same thing in those respective events. Updated fiddle and code snippet above.
Edit:
If the expected usability is to be able to paste/drop partial numbers into the field and to not allow negative integers, then you can just change how int is defined in the ensureIntegerValueOnPaste function. Updated fiddle and code snippet above.
You don't need regular expression, you can use parseFloat() function. Your input type remains unchanged, there are still "arrows" to increase/decrease number and also it makes sure that your input will not start with zero.
document.getElementById("integer").addEventListener('input', restrictToInteger);
function restrictToInteger() {
this.value = parseFloat(this.value);
}
<input type="number" id="integer" />
You have to check if the value is not a number and then stop user.
document.getElementById("integer").addEventListener('input', restrictToInteger);
function restrictToInteger(e)
{
if(isNaN(e.data)){
alert("only numbers allowed");
}
}
<input type="number" id="integer" />
I am trying to check only alphabet in textbox(like XYZ) and any alphanumeric or special character value not entered. But my function only check numeric value and one more condition applied, if i pass alphanumeric value or special character in the textbox with alphabet or without alphabet then it will be not accept the textbox value. So please help me..
<script>
function Enable() {
var txt = document.getElementById("textbox");
if (!isNaN(txt.value) || txt.value == "") {
alert("Blank or numeric value");
}
else
alert("Not numeric value");
}
</script>
<input type="button" onclick="Enable();" value="Add" />
<input type="text" id="textbox" />
You can try this regex to validate the input in the input box:
/^a-zA-Z$/i
You can bind the keyup event. When the event triggers, validate the value of the input box against the above mentioned regex, and replace with the desired value. Something like this:
$(this).val($(this).val().replace(/[^a-zA-Z]/g, ''));
I'm trying to get my login form to only validate if only numbers were inputted. I can it to work if the input is only digits, but when i type any characters after a number, it will still validate etc. 12akf will work. 1am will work. How can i get past this?
Part of the Login
<form name="myForm">
<label for="firstname">Age: </label>
<input name="num" type="text" id="username" size="1">
<input type="submit" value="Login" onclick="return validateForm()">
function validateForm()
{
var z = document.forms["myForm"]["num"].value;
if(!z.match(/^\d+/))
{
alert("Please only enter numeric characters only for your Age! (Allowed input:0-9)")
}
}
Match against /^\d+$/. $ means "end of line", so any non-digit characters after the initial run of digits will cause the match to fail.
Edit:
RobG wisely suggests the more succinct /\D/.test(z). This operation tests the inverse of what you want. It returns true if the input has any non-numeric characters.
Simply omit the negating ! and use if(/\D/.test(z)).
here is how to validate the input to only accept numbers this will accept numbers like 123123123.41212313
<input type="text"
onkeypress="if ( isNaN(this.value + String.fromCharCode(event.keyCode) )) return false;"
/>
and this will not accept entering the dot (.), so it will only accept integers
<input type="text"
onkeypress="if ( isNaN( String.fromCharCode(event.keyCode) )) return false;"
/>
this way you will not permit the user to input anything but numbers
This one worked for me :
function validateForm(){
var z = document.forms["myForm"]["num"].value;
if(!/^[0-9]+$/.test(z)){
alert("Please only enter numeric characters only for your Age! (Allowed input:0-9)")
}
}
Late answer,but may be this will help someone
function isNumber(n) {
return !isNaN(parseFloat(n)) && isFinite(n);
}
Use will be like
nn=document.forms["myForm"]["num"].value;
ans=isNumber(nn);
if(ans)
{
//only numbers
}
This ans was found from here with huge vote
Validate numbers in JavaScript - IsNumeric()
function validateNumber(e) {
const pattern = /^[0-9]$/;
return pattern.test(e.key )
}
<input name="username" id="username" onkeypress="return validateNumber(event)">
This approach doesn't lock numlock numbers, arrows, home, end buttons and etc
The simplest solution.
Thanks to my partner that gave me this answer.
You can set an onkeypress event on the input textbox like this:
onkeypress="validate(event)"
and then use regular expressions like this:
function validate(evt){
evt.value = evt.value.replace(/[^0-9]/g,"");
}
It will scan and remove any letter or sign different from number in the field.
No need for the long code for number input restriction just try this code.
It also accepts valid int & float both values.
Javascript Approach
onload =function(){
var ele = document.querySelectorAll('.number-only')[0];
ele.onkeypress = function(e) {
if(isNaN(this.value+""+String.fromCharCode(e.charCode)))
return false;
}
ele.onpaste = function(e){
e.preventDefault();
}
}
<p> Input box that accepts only valid int and float values.</p>
<input class="number-only" type=text />
jQuery Approach
$(function(){
$('.number-only').keypress(function(e) {
if(isNaN(this.value+""+String.fromCharCode(e.charCode))) return false;
})
.on("cut copy paste",function(e){
e.preventDefault();
});
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<p> Input box that accepts only valid int and float values.</p>
<input class="number-only" type=text />
The above answers are for most common use case - validating input as a number.
But to allow few special cases like
negative numbers & showing the invalid keystrokes to user before
removing it, so below is the code snippet for such special use cases.
$(function(){
$('.number-only').keyup(function(e) {
if(this.value!='-')
while(isNaN(this.value))
this.value = this.value.split('').reverse().join('').replace(/[\D]/i,'')
.split('').reverse().join('');
})
.on("cut copy paste",function(e){
e.preventDefault();
});
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<p> Input box that accepts only valid int and float values.</p>
<input class="number-only" type=text />
Regular expressions are great, but why not just make sure it's a number before trying to do something with it?
function addemup() {
var n1 = document.getElementById("num1");
var n2 = document.getElementById("num2");
sum = Number(n1.value) + Number(n2.value);
if(Number(sum)) {
alert(sum);
} else {
alert("Numbers only, please!");
};
};
function ValidateNumberOnly()
{
if ((event.keyCode < 48 || event.keyCode > 57))
{
event.returnValue = false;
}
}
this function will allow only numbers in the textfield.
I think we do not accept long structure programming we will add everytime shot code see below answer.
<input type="text" oninput="this.value = this.value.replace(/[^0-9.]/g, ''); this.value = this.value.replace(/(\..*)\./g, '$1');" >
Using the form you already have:
var input = document.querySelector('form[name=myForm] #username');
input.onkeyup = function() {
var patterns = /[^0-9]/g;
var caretPos = this.selectionStart;
this.value = input.value.replace(patterns, '');
this.setSelectionRange(caretPos, caretPos);
}
This will delete all non-digits after the key is released.
var elem = document.getElementsByClassName("number-validation"); //use the CLASS in your input field.
for (i = 0; i < elem.length; i++) {
elem[i].addEventListener('keypress', function(event){
var keys = [48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 0];
var validIndex = keys.indexOf(event.charCode);
if(validIndex == -1){
event.preventDefault();
}
});
}
If you are using React, just do:
<input
value={this.state.input}
placeholder="Enter a number"
onChange={e => this.setState({ input: e.target.value.replace(/[^0-9]/g, '') })}
/>
<div id="root"></div>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.4.2/react.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.4.2/react-dom.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/babel-standalone/6.21.1/babel.min.js"></script>
<script type="text/babel">
class Demo extends React.Component {
state = {
input: '',
}
onChange = e => {
let input = e.target.value.replace(/[^0-9]/g, '');
this.setState({ input });
}
render() {
return (
<div>
<input
value={this.state.input}
placeholder="Enter a number"
onChange={this.onChange}
/>
<br />
<h1>{this.state.input}</h1>
</div>
);
}
}
ReactDOM.render(<Demo />, document.getElementById('root'));
</script>
// I use this jquery it works perfect, just add class nosonly to any textbox that should be numbers only:
$(document).ready(function () {
$(".nosonly").keydown(function (event) {
// Allow only backspace and delete
if (event.keyCode == 46 || event.keyCode == 8) {
// let it happen, don't do anything
}
else {
// Ensure that it is a number and stop the keypress
if (event.keyCode < 48 || event.keyCode > 57) {
alert("Only Numbers Allowed"),event.preventDefault();
}
}
});
});
Avoid symbols like "." "," "+" "-". I tried it and it works fine.
$('#example').keypress(function (evt) {
if (evt != null && evt.originalEvent != null && /\D/.test(evt.originalEvent.key)) {
evt.preventDefault();
evt.stopImmediatePropagation();
return false;
}
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<input name="example" id="example">