How to validate decimal number using JavaScript?
Following example shows you to validate a decimal number in javascript as a client side validation
In some situations you may want to validate a decimal number before submitting your form. It is good practice to validate input data before they sent to the web server. Using a simple javascript you can validate a decimal number. A decimal number contains 0 to 9 integer values and only one decimal point. There is an in-built function isNaN() that can use to validate a decimal number in javascript.
Using following javascript you can check
whether a particular number is a valid decimal number of not.
Using following javascript you can check
whether a particular number is a valid decimal number of not.
Demo- Validate Decimal Number In JavaScript
Enter a value and click on submit button to test whether input is a valid decimal number or not. If you enter an invalid decimal number JavaScript alerts you, you have entered an invalid number. Otherwise it alerts the input is a valid decimal number.
1. Validate decimal number. | ||
Enter a Decimal Number | ||
view code | ||
2. How to validate a decimal number on key press event. | ||
Enter a number | view code | |
3. Use following code to validate a decimal number with specified decimal places. | ||
Number of Decimal Points | view code | |
Enter Decimal Number | ||
Enter a value and click on submit button to test whether input is a valid decimal number or not. If you enter an invalid decimal number JavaScript alerts you, you have entered an invalid number. Otherwise it alerts the input is a valid decimal number.
1. Example code for validate a decimal number in JavaScript.
JavaScript Code<script type="text/javascript" language="javascript">
<!--
function validateDecimalNumber(){
var value = document.getElementById("textDecimalNumber").value;
var message = "Please enter a decimal value";
if(value!=""){
if(isNaN(value)==true){
alert(message);
return false;
}else{
alert(value+" is a valid decimal number");
return true;
}
}else{
alert(message);
return false;
}
return false;
}
-->
</script>
<!--
function validateDecimalNumber(){
var value = document.getElementById("textDecimalNumber").value;
var message = "Please enter a decimal value";
if(value!=""){
if(isNaN(value)==true){
alert(message);
return false;
}else{
alert(value+" is a valid decimal number");
return true;
}
}else{
alert(message);
return false;
}
return false;
}
-->
</script>
Html Code
<html>
<head>
<title>How to Validate Decimal Number in JavaScript </title>
</head>
<body>
<table border="0">
<tr>
<td>Enter Decimal Number </td>
<td>
<input name="textDecimalNumber" type="text" id="textDecimalNumber" />
</td>
</tr>
<tr>
<td> </td>
<td>
<input name="btnDecimalNumberValidator" type="submit" id="btnDecimalNumberValidator" onclick="javascript:validateDecimalNumber();" value="Validate" />
</td>
</tr>
</table>
</body>
</html>
2. Example code for validate a decimal number on key press event in JavaScript.
JavaScript Code<script type="text/javascript" language="javascript">
<!--
function validate(){
var value = document.getElementById("txtDecimal").value;
var message = "Please enter a decimal value";
if(isNaN(value)==true){
alert(message);
document.getElementById("txtDecimal").select();
return false;
}else{
return true;
}
}
-->
</script>
<!--
function validate(){
var value = document.getElementById("txtDecimal").value;
var message = "Please enter a decimal value";
if(isNaN(value)==true){
alert(message);
document.getElementById("txtDecimal").select();
return false;
}else{
return true;
}
}
-->
</script>
Html Code
<html>
<head>
<title>How to Validate Decimal Number in KeyPress Event in JavaScript </title>
</head>
<body>
<table border="0">
<tr>
<td>Enter Decimal Number </td>
<td>
<input name="textDecimalNumber" type="text" id="textDecimalNumber" />
</td>
</tr>
<tr>
<td> </td>
<td>
<input name="txtDecimal" type="text" id="txtDecimal" onkeyup="javascript:validate();" />
</td>
</tr>
</table>
</body>
</html>
3. Custom Decimal number validation using JavaScript.
<script type="text/javascript" language="javascript">
<!--
<!--
//------------------------------------------------------------------
function showDecimalPointError(){
var message="Please enter an integer value";
alert(message);
document.getElementById("textDecimalPoints").value="2";
return false;
}
//------------------------------------------------------------------
function CheckDecimalPoints(){
var decimalPoints=document.getElementById("textDecimalPoints").value;
for(var x=0;x<decimalPoints.length;x++){
if(decimalPoints.charAt(x)=="."){
showDecimalPointError();
}
if(isNaN(decimalPoints.charAt(x))){
showDecimalPointError();
}
}
return true;
}
//------------------------------------------------------------------
function customValidation(){
var preferredDecimalPoints=document.getElementById("textDecimalPoints").value;
var decimalPointCount=0;
var decimalNumber = document.getElementById("txtCustomValidation").value;
var pointFound=false;
var decimalPlaces=0;
for(var i=0;i< decimalNumber.length ;i++){
var _char=decimalNumber.charAt(i);
if(pointFound==true){
decimalPlaces++;
}
if(_char=="."){
pointFound=true;
decimalPointCount++;
if(decimalPointCount>1){
break;
}
}else if(isNaN(_char)){
setError()
return false;
}
}
if(decimalPointCount!=1){
setError()
return false;
}else if(decimalPlaces!=preferredDecimalPoints){
setError()
return false;
}else if(isNaN(decimalNumber)){
setError()
}else{
alert(decimalNumber+" is a valid decimal number");
}
return true;
}
//------------------------------------------------------------------
function setError(){
var message="Please enter a valid decimal number";
alert(message);
document.getElementById("txtCustomValidation").select();
document.getElementById("txtCustomValidation").focus();
return false;
}
//-------------------------------------------------------------------->
</script>
function showDecimalPointError(){
var message="Please enter an integer value";
alert(message);
document.getElementById("textDecimalPoints").value="2";
return false;
}
//------------------------------------------------------------------
function CheckDecimalPoints(){
var decimalPoints=document.getElementById("textDecimalPoints").value;
for(var x=0;x<decimalPoints.length;x++){
if(decimalPoints.charAt(x)=="."){
showDecimalPointError();
}
if(isNaN(decimalPoints.charAt(x))){
showDecimalPointError();
}
}
return true;
}
//------------------------------------------------------------------
function customValidation(){
var preferredDecimalPoints=document.getElementById("textDecimalPoints").value;
var decimalPointCount=0;
var decimalNumber = document.getElementById("txtCustomValidation").value;
var pointFound=false;
var decimalPlaces=0;
for(var i=0;i< decimalNumber.length ;i++){
var _char=decimalNumber.charAt(i);
if(pointFound==true){
decimalPlaces++;
}
if(_char=="."){
pointFound=true;
decimalPointCount++;
if(decimalPointCount>1){
break;
}
}else if(isNaN(_char)){
setError()
return false;
}
}
if(decimalPointCount!=1){
setError()
return false;
}else if(decimalPlaces!=preferredDecimalPoints){
setError()
return false;
}else if(isNaN(decimalNumber)){
setError()
}else{
alert(decimalNumber+" is a valid decimal number");
}
return true;
}
//------------------------------------------------------------------
function setError(){
var message="Please enter a valid decimal number";
alert(message);
document.getElementById("txtCustomValidation").select();
document.getElementById("txtCustomValidation").focus();
return false;
}
//-------------------------------------------------------------------->
</script>
Html Code
<html>
<head>
<title>How to Validate Decimal Number in JavaScript </title>
</head>
<body><table border="0">
<tr>
<td>Number of Decimal Points </td>
<td><label>
<input name="textDecimalPoints" type="text" id="textDecimalPoints" size="5" value="2" onkeyup="javascript:CheckDecimalPoints();" " />
</label></td>
</tr>
<tr>
<td>Enter Decimal Number </td>
<td><label>
<input name="txtCustomValidation" type="text" id="txtCustomValidation" />
</label></td>
</tr>
<tr>
<td> </td>
<td><label>
<input name="btnCustomValidation" type="submit" id="btnCustomValidation" value="Validate" onclick="javascript:customValidation();" />
</label></td>
</tr>
</table></body>
</html>
<head>
<title>How to Validate Decimal Number in JavaScript </title>
</head>
<body><table border="0">
<tr>
<td>Number of Decimal Points </td>
<td><label>
<input name="textDecimalPoints" type="text" id="textDecimalPoints" size="5" value="2" onkeyup="javascript:CheckDecimalPoints();" " />
</label></td>
</tr>
<tr>
<td>Enter Decimal Number </td>
<td><label>
<input name="txtCustomValidation" type="text" id="txtCustomValidation" />
</label></td>
</tr>
<tr>
<td> </td>
<td><label>
<input name="btnCustomValidation" type="submit" id="btnCustomValidation" value="Validate" onclick="javascript:customValidation();" />
</label></td>
</tr>
</table></body>
</html>
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