<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8" name="viewport" content="width=device-width, initial-scale=1"/> <link rel="stylesheet" type="text/css" href="css/bootstrap.css" /> </head> <body> <nav class="navbar navbar-default"> <div class="container-fluid"> </div> </nav> <div class="col-md-6 well"> <hr style="border-top:1px dotted #ccc;"/> <div class="col-md-6"> <div class="form-group"> <input type="text" id="digit" class="form-control"/> <br /> <br /> </div> </div> </div> </body> </html>
function checkNumber(){ var digit = document.getElementById('digit').value; if(digit === ""){ alert("Please complete the required field"); }else{ if (digit >= 0) { result = "<center><span style='font-size:20px;' class='text-primary'>"+digit + "</span> is not a Negative Number.</center>"; document.getElementById('result').innerHTML = result; }else{ result = "<center><span style='font-size:20px;' class='text-danger'>"+digit + "</span> is a Negative Number.</center>"; document.getElementById('result').innerHTML = result; } } }