Help with Javascript Validation

philmccollam · 09-19-2012, 03:13 PM

Hello!

I'm putting together a very small project that requires the user to enter their age when they initially land on the homepage, via prompt. That age is then compared to a random number between 1 and 30; if their age is higher, they are directed to page A and if their age is lower, they are directed to page B.

I have the prompt and redirections set up, but what I'm now trying to do is set up an alert so that if the user does NOT fill in their age, they are forced to do so before moving on to one of the two pages (A or B, depending). At the moment, the alert shows up when either the "Cancel" or "OK" button is clicked during the initial prompt, but I cannot get the prompt to reappear after clicking "OK" on the alert.

My code is as follows:

Code:

$(window).load(function() {
			
  var agePrompt=prompt("You should probably lie about your age:");
  var randomnumber=Math.floor(Math.random()*31)
				
  if (agePrompt==null || agePrompt=="") {
    alert("You MUST lie about your age");
    return false;
  }
  else {
    if (agePrompt>=randomnumber) window.location.href="too-old.htm";
    else {
      window.location.href="take-a-seat.htm";
    }
  }
});

The actual page can be found here: http://philrules.com/17-tips/week-16/

Any help would be greatly appreciated — even if you can just point me towards a resource!

Thanks,

Phil

AndrewGSW · 09-19-2012, 03:25 PM

prompt() returns a string so you need to convert it to a number before comparing it to randomnumber:

Code:

agePrompt = parseInt(agePrompt);

Philip M · 09-19-2012, 03:29 PM

prompt() is a very primitive way of obtaining user input. But to avoid the ugly undefined in the prompt

Code:

var agePrompt=prompt("You should probably lie about your age:","");

philmccollam · 09-19-2012, 08:15 PM

Thanks for the help! I agree that the prompt() is not the best way to do it, so I set up a new version that should use text input to verify the age of the user. However, I'm not versed in script well enough to make it actually function.

Here is what I have now: (also viewable at http://philrules.com/17-tips/week-16/)

Code:

$(window).load(function verify() {
  var ageNum=parseInt(document.forms["age-verification"]["age"].value);
  var randomNumber=Math.floor(Math.random()*31)
				
  if (ageNum==null || ageNum=="") {
    return false;
    }
    else {
      if (ageNum>=randomNumber)window.location.href="too-old.htm";
      else {
        window.location.href="take-a-seat.htm";
      }
    }
  });

The form I have set up to interact with this script is:

Code:

<form name="age-verification" onSubmit="verify()";>

<label>Age</label>
<input name="age" type="text" size="3" maxlength="2">

<input name="Submit" type="Submit">
</form>

My apologies if this is all syntactically horrendous; I'm still learning the language.

Best,

Phil

Philip M · 09-19-2012, 08:56 PM

Code:

<html>
<head>
</head>

<body>

<script type = "text/javascript">

function verify() {
var ageNum=parseInt(document.forms["age-verification"]["age"].value,10);//  if you use parseInt() youmust specify the radix
var randomNumber=Math.floor(Math.random()*31);
if (isNaN(ageNum)) {
alert ("Please enter a numeric value for age");
document.forms["age-verification"]["age"].value = "";
return false;
}

if (ageNum>=randomNumber){window.location.href="too-old.htm"}
else { window.location.href="take-a-seat.htm";  }

}

</script>

<form name="age-verification" >

<label>Age</label>
<input name="age" type="text" size="3" maxlength="2">
<input name="b1" type="button" value = "Verify" onclick = "verify()">
</form>

</body>
</html>

Old Pedant · 09-20-2012, 07:04 AM

Shoot, if most of us REAL coders here entered our REAL age, he wouldn't be sending any of us to take-a-seat.htm

Now, if he made it a random number from 1 to 75, say, at least I'd have ALMOST an 11% chance.

Philip M · 09-20-2012, 08:13 AM

Quote:

Originally Posted by Old Pedant

Shoot, if most of us REAL coders here entered our REAL age, he wouldn't be sending any of us to take-a-seat.htm

Now, if he made it a random number from 1 to 75, say, at least I'd have ALMOST an 11% chance.

I have the idea that if you entered your real age you would be (far) too old for him to be interested in you.