JSFiddle - React, Tailwind, and code Playground

by pj_js15

HTML

<input type="text" id="txtSample" />

CSS

.notValid {
  border: 1px solid red;   
}

JavaScript

$().ready(function(){
   
  //var test = validateOne('test');
  
  $('#txtSample').keyup(function() {
      var result = validateOne( $(this).val() );
      if(!result){
          $(this).addClass('notValid');            
      }
      else{
          $(this).removeClass('notValid');    
      }
  });      
    
});


function validateOne(input)
{
    var regexVal = /^(N)?\d*([0-9])?$/;
       // /^N\d*([0-9])?$/;
    
    return regexVal.test(input);
//^N([0-9])    
}