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Implement JS NumberFormat Function

Hi guys I am brand new to JS and building a small calculator project just to learn:

Calculator is working and I a now trying to implement a Format function I got by googling. I am obviously doing something wrong because all my attempts fail and in fact stop the rest of my JS from running

Here is what I have:

The line in red is my attempt at implementing the formatDollar( ) function

Can someone show me where I am going wrong

Thanks

Code:

<script type="text/javascript">

<!-- 



function formatDollar(value) {

    var p = num.toFixed(2).split(".");

    return "$" + p[0].split("").reverse().reduce(function(acc, num, i, orig) {

        return  num + (i && !(i % 3) ? "," : "") + acc;

    }, "") + "." + p[1];

}

function centNotation(value)

 { 



 dollars = Math.floor(value); // chop floating point portion 

 cents = Math.floor((value % 1) * 100); // and chop everything else

 if (cents < 10) cents = "" + cents + "0";

 return(dollars + "." + cents);

 }





function validInt(value)

{

  



  for (var i=0; i < value.length; i++) {

    var c = value.charAt(i);

    if ((c < '0' || c > '9') && c != '.') {

      alert("There's a problem: all values herein must " +

        "be numbers only, and " + value + " has an unacceptable character " +

        "'" + c + "'");

      return(false);

    }

  }

  return(true);

}



function myPaymentCalc()

{

  

  

  var interestRate = document.debtcalc.interest.value,

      monthlyPayment = document.debtcalc.monthlypayment.value,

      principal = document.debtcalc.principal.value,

      accumulatingInterest = 1;

  

  if (! validInt(interestRate) || ! validInt(monthlyPayment) ||

      ! validInt(principal))

    return(false);

    

  if (interestRate == 0 || monthlyPayment == 0 || principal == 0) {

    alert("You need to specify your monthly payment, credit card " +

        "interest rate and current debt amount before I can calculate " +

        "how long it'll take for you to pay off your debt.");

    return(false);

  }

  

  interestRate = (interestRate > 1)? interestRate / 100.0 : interestRate;



  monthlyInterestRate = interestRate / 12;



  if (principal * monthlyInterestRate > monthlyPayment) {

    monthlyrate = "$" + centNotation(principal * monthlyInterestRate);

    permonthPayment = "$" + centNotation(monthlyPayment);

    alert("You've got a fundamental problem: your monthly payment of " +

        permonthPayment + " is less than the interest added each month " +

        "(which is " + monthlyrate + ") and you will never " +

        "pay off this debt. It might be a good time to call your creditors.");

    return(false);

  }

   

  interimVal1 = monthlyPayment - (monthlyInterestRate * principal)

  

  numberOfPayments = (Math.log(monthlyPayment) - Math.log(interimVal1)) /

        Math.log(1+monthlyInterestRate);

  

  numberOfPayments = Math.ceil(numberOfPayments);

      

  interimVal2 = Math.pow((monthlyInterestRate+1), (numberOfPayments-1));

  

  remaining = (principal * interimVal2) -

    (monthlyPayment/monthlyInterestRate) * (interimVal2 - 1);

    

  totalPayment = monthlyPayment *(numberOfPayments-1) + remaining;

  

 

        

  payments = numberOfPayments;



  totalpayment = "$" + centNotation(totalPayment);



  totalpaymentamt= formatDollar(totalpayment);



  interestPaid = "$" + centNotation(totalPayment-principal);         

  alert("Given these figures, you'll end up having " + payments +

        " payments and pay a total of " + totalpayment + ", of which " +

        interestPaid + " is interest.");      

        

        document.debtcalc.numberofpayments.value = payments;

        document.debtcalc.totalpayments.value = totalpayment;        

        document.debtcalc.intpmt.value = interestPaid;

          



}









// -->

</script>

Did you take a look at the formatDollar function? It's pretty obvious that it cannot work if you name the parameter "value" in the head, but the function tries to work on a variable named "num". It just doesn't fit. There might be more wrong, but I didn't look further into it as this is the first mistake. Once you fixed this, please use the console to check what error you are getting – maybe you can fix it yourself.

Also, when you post source code, please use the [ code ] tags to that it looks better and is readable.

This is crazy:

Code:

function validInt(value)

{

    for (var i=0; i < value.length; i++) {

        var c = value.charAt(i);

        if ((c < '0' || c > '9') && c != '.') {

            alert("There's a problem: all values herein must " +

                    "be numbers only, and " + value + 

                    " has an unacceptable character " + "'" + c + "'");

            return(false);

       }

    }

    return(true);

}

validInt??? Integers do *NOT* have decimal points, so what in the world is the test for period doing in there?

On top of that, as written that code would *ALLOW* input such as ".........." or "3........9" or "3.999999999999", none of which make a lot of sense.

If you want to check for a valid number--and here I will assume it is to be no more than 2 digits after the decimal point (i.e., dollars and cents) then:

Code:

function validNum( value )

{

    if ( ( /^\-?(\.\d\d?|\d+(\.\d?\d?)?)$/ ).test( value ) { return true; }

    document.getElementById("errorMessage") = 

          "That is not a valid dollars and cents value";

    return false;

}

The \-? in red is optional, if you want to allow negative numbers.

Notice that this also avoids the use of alert( ), which is obsolete.

But if you aren't so fussy--if you *WILL* allow numbers such as 3.9999999 or 13E2--then let JS test for you:

Code:

if ( isNaN( value ) ) { ... not a valid number ... } else { ... valid ... }

Thanks Airblader I changed the parameter to num still not working and i have know Idea how to use "console" but will google and look into that

Thanks Old Pedant , that was also a piece of code I found googling, I actually do want to allow for decimals even though the function says "validInt" but thanks for explaing the other problems, once i figure out the problem with the question in my original post I will move onto that

Figured out how to get debugger in IE and there is an error

SCRIPT438: Object doesn't support property or method 'reduce'

Found a work around to the error message with this piece of code:

Code:

if (!Array.prototype.reduce) {

  Array.prototype.reduce = function reduce(accumulator){

    if (this===null || this===undefined) throw new TypeError("Object is null or undefined");

    var i = 0, l = this.length >> 0, curr;



    if(typeof accumulator !== "function") // ES5 : "If IsCallable(callbackfn) is false, throw a TypeError exception."

      throw new TypeError("First argument is not callable");



    if(arguments.length < 2) {

      if (l === 0) throw new TypeError("Array length is 0 and no second argument");

      curr = this[0];

      i = 1; // start accumulating at the second element

    }

    else

      curr = arguments[1];



    while (i < l) {

      if(i in this) curr = accumulator.call(undefined, curr, this[i], i, this);

      ++i;

    }



    return curr;

  };

}

See the answer you were given in the thread you have hijacked.

http://www.codingforums.com/showthread.php?t=286939

Quote:

Originally Posted by Philip M (Post 1310638)

See the answer you were given in the thread you have hijacked.

http://www.codingforums.com/showthread.php?t=286939

I didnt ask another question, I posted what appeared to be a soluton for others to see.

Wasn't aware I hijacked a thread, I asked a question that was relevant to the OP question in that thread. My apologies if that was not appropriate
"Supreme Master Coder" :)

Quote:

Originally Posted by billboy (Post 1310729)

You asked "How can you get the value from a JS function that is in a seperate file to an inputbox on another page?". That is termed hijacking. Prefer to start your own thread if you want to raise a new issue.

Quote:

Originally Posted by Philip M (Post 1310776)

Yes but the OP was on implementing js from external file?

Anyway, again my apologies, I certainly didnt intend to "hijack" anyones post, in the future I will start a new post

Thanks

Quote:

Originally Posted by billboy (Post 1310890)

Yes but the OP was on implementing js from external file?

That's how ALL JavaScript should be implemented.