JSFiddle - React, Tailwind, and code Playground

by Filipe Augusto Lima de Souza

HTML

<h3>With parseFloat</h3>
<form method="post">
<input type="text" id="number"value="" />
<input id="submit" type="submit" onclick="return validateNumber();"/> 
</form>

<h3>Checking the value directly</h3>
<form method="post">
<input type="text" id="number2"value="" />
<input id="submit2" type="submit" onclick="return validateNumber2();"/> 
</form>

JavaScript

$('#submit').on('click', function(e) { 
    e.preventDefault();
    validateNumber();
});

function validateNumber()
{
   var number = $('#number').val();
   var cnumber = parseFloat(number);
   
   if(isNaN(cnumber))
   {
    alert("only number");
    return false;
   }
   return true;
 }

$('#submit2').on('click', function(e) { 
    e.preventDefault();
    validateNumber2();
});

function validateNumber2()
{
   var number = $('#number2').val();
   
   if(isNaN(number))
   {
    alert("only number");
    return false;
   }
   return true;
 }