CODEWITHSUNDEEP
javascriptundefinednan
Tom Hewitt
Tom Hewitt

Reputation: 13

Javascript number is NaN

I've been looking around and I can't seem to find out why this is happening or how to fix it. I've been trying different things for about 2 days, now its time to ask for help before I rip the rest of my hair out (I'm new to Java)

I know the code is very long winded at the moment, but its like that for readability to see why its not working for me.

     function getBaB()
{   
      var BaB=0;
      var theForm = document.forms["prrform"];
      var basebab = theForm.elements["charbab"];
      BaB = basebab.value;
      return BaB;
}

 var armour_types = new Array();

//This is the bit that doesn't work

 armour_types["Heavy"] = (getBaB.value) ;

//It just returns undefined, and if I parseInt then I get NaN. I just can't see why it isn't defined.

 armour_types["Medium"] = 10;
 armour_types["Light"] = 2;
 armour_types["Adamantine"] = 10;
 armour_types["Mithral"] = 5;
 armour_types["Unarmoured"] = 0;


function calculateTotal()
{
   var TotalPRR = getArmourType();
    var divobj = document.getElementById('totalPRR');
    divobj.style.display='block';
    divobj.innerHTML = "Total PRR "+TotalPRR;

}

function hideTotal()
{
    var divobj = document.getElementById('totalPRR');
    divobj.style.display='none';
}

I can post the HTML if needed.

Thanks in advance :

Upvotes: 1

Views: 277

Answers (3)

Chris GW Green
Chris GW Green

Reputation: 1199

Kirubhananth Chellam is correct with his answer:

armour_types["Heavy"] = getBaB();

But as you're new to Javascript (Java has a very different syntax) I'll try an explain where you're going abit wrong an see if I can help you further.

Javascript is loosely typed - and this is key to the entire language. Consider...

var x = 0;

... as you imagine assigns value 0 to x. Simple but a key starting point as the assignment... 

x = "hello"

... is not so simple to understand. In strongly typed languages, this would return a type error however is Javasript, this is perfectly acceptable. As is...

x = function(){
    var y = 0;
    return y;
}

...even after x has been assigned a numeric value.

The reason this is important as when Javascript is interpreted at runtime, function declarations such as...

function x(){
    ...
}

... are actually interpreted in the same way as variable assignments...ie....

var x = function(){
    ...
}

...which can result in odd behaviour if you overload the variable x (see Hoisting http://www.adequatelygood.com/JavaScript-Scoping-and-Hoisting.html).

Returning to your question, the call to getBaB.value means you're calling for getBaB as a variable assigned an object with an attribute called 'value'.

In your code, Javascript will return the function definition (which is technically an object) as the value getBaB which doesn't have a 'value' attribute and thus undefined.

Note: Attempting to Parse undefined as an int oddly returns NaN (not undefined).

As for your function...

  function getBaB()
{   
      var BaB=0;
      var theForm = document.forms["prrform"];
      var basebab = theForm.elements["charbab"];
      BaB = basebab.value;
      return BaB;
}

return BaB does not return an object, though you might think it does. Returning to javascript being loosely typed; BaB = basebab.value; would mean BaB is a assigned a numeric value and not an object with a 'value' attribule.

Interestingly, getBaB() could still return 'undefined' if theForm.elements["charbab"]; is not found and 'null' if a value is not set in 'charbab' as it overrides BaB = 0 (loosely typed ;)).

As such I'd suggest you make sure basebab returns a logical value to ensure your code behaves reliably with a quick if statement!

Hope this helps.

GW

Upvotes: 1

Kirubhananth Chellam
Kirubhananth Chellam

Reputation: 72

First the the getBAB() must return an array. I have an example from your code as follows

   function BlockID() {
        var IDs = new Array();
        IDs[0] = "a";
        IDs[1] = "b";
        IDs[2] = "c";
        IDs[3] = "d";
        return IDs;
 }

  var isReady = true;
  function doSaveAs(){
    var armour_types = new Array();
    armour_types["Heavy"] = BlockID();
  }

 <body>
     <input type="button" onClick="doSaveAs();">click</input>
 </body>

Upvotes: 0

Kirubhananth Chellam
Kirubhananth Chellam

Reputation: 72

Your method calling is wrong. Just call the method as methodname();

So, In your code

  armour_types["Heavy"] = getBaB();

will work i guess.

Upvotes: 0

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