JavaScript: Calculator Script - INTEREST CALCULATOR

Main Calculator Script INTEREST CALCULATOR

<!-- TWO STEPS TO INSTALL INTEREST CALCULATOR:

1.  Paste the coding into the HEAD of your HTML document

2.  Copy the last code into the BODY of your HTML document  -->

<HEAD><title>JavaScript, java script, javascripts, script, javascript free code!</title>

<!-- Begin

function checkNumber(input, min, max, msg) {

msg = msg + " field has invalid data: " + input.value;

var str = input.value;

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

var ch = str.substring(i, i + 1)

if ((ch < "0" || "9" < ch) && ch != '.') {

alert(msg);

return false;

}

var num = parseFloat(str)

if (num < min || max < num) {

alert(msg + " not in range [" + min + ".." + max + "]");

return false;

}

input.value = str;

return true;

}

function computeField(input) {

if (input.value != null && input.value.length != 0)

input.value = "" + eval(input.value);

computeForm(input.form);

}

function computeForm(form) {

if ((form.payments.value == null || form.payments.value.length == 0) ||

(form.interest.value == null || form.interest.value.length == 0) ||

(form.principal.value == null || form.principal.value.length == 0)) {

return;

}

if (!checkNumber(form.payments, 1, 480, "# of payments") ||

!checkNumber(form.interest, .001, 99, "Interest") ||

!checkNumber(form.principal, 100, 10000000, "Principal")) {

form.payment.value = "Invalid";

return;

}

var i = form.interest.value;

if (i > 1.0) {

i = i / 100.0;

form.interest.value = i;

}

i /= 12;

var pow = 1;

for (var j = 0; j < form.payments.value; j++)

pow = pow * (1 + i);

money = "" + .01* Math.round(100*(form.principal.value * pow * i) / (pow - 1));

dec = money.indexOf(".");

dollars = money.substring(0,dec);

cents = money.substring(dec+1,dec+3);

cents = (cents.length < 2) ? cents + "0" : cents;

money = dollars + "." + cents;

form.payment.value = money;

}

function clearForm(form) {

form.payments.value = "";

form.interest.value = "";

form.principal.value = "";

}

// done hiding from old browsers -->

</SCRIPT>

<BODY>

<TR>

<TD>

<DIV ALIGN=CENTER>  # of<br>Payments</DIV>

</TD>

<TD>

<DIV ALIGN=CENTER>Interest<br>Rate</DIV>

</TD>

<TD>

<DIV ALIGN=CENTER>Principal</DIV>

</TD>

<TD>

</TD>

<TD>

<DIV ALIGN=CENTER> Monthly<br> Payment</DIV>

</TD>

</TR>

<TR>

<TD>

</TD>

<TD>

</TD>

<TD>

</TD>

<TD>

</TD>

<TD>

</TD>

<TD>

</TD>

<TD>

</TD>

</TR>

</FORM>

<TR>

<TD>

</TD>

<TD>

</TD>

<TD>

</TD>

<TD>

</TD>

<TD>

</TD>

<TD>

</TD>

<TD>

</TD>

</TR>

</FORM>

<TR>

<TD>

</TD>

<TD>

</TD>

<TD>

</TD>

<TD>

</TD>

<TD>

</TD>

<TD>

</TD>

<TD>

</TD>

</TR>

</TABLE>

</FORM>

</CENTER>

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</center><p>

Click Here if you need help to install the JavaScript

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