Question

<SCRIPT Language = JavaScript>
function calculate() {
a = 12
b = eval(document.form.number.value)
c = 5J7S
d = (a + b + c)
alert(d)

}
</SCRIPT>

<FORM NAME = form>

Phone: <INPUT TYPE = text SIZE = 3 value ="">
-
<INPUT TYPE = text name = number SIZE = 3 value ="">
-
<INPUT TYPE = text SIZE = 4 value ="">

<P>
<Input Type = Button NAME = b1 VALUE = "Grab Code" onClick = calculate() 

</FORM>

5JG7S (Fixed Value)

5+7=12 (Added both numbers from Fixed Value)

Phone number 123-456-7890
4+5+6=15 (Prefix added together)
12+15=27 (Added numbers from the Fixed Value and the numbers that were added from the prefix)
27+5JG7S=275JG7S (Those numbers were added to the beginning of the orginal Fixed Value)

Now this Script that I have:
a is the added numbers from the Fixed Value
b is the input from the form(phone number)
c is the Fixed Value
d is adding each one up so they will display the code as an alert.

Now, if I take out c and just add a and b it performs the addition, if c is in there, it stops the process and produces nothing.

My question is, how do we add the calculated number and append it to the beginning of the fixed value?

Also, the addition works, but not the way I want it to, I want to add the 3 numbers together, the javascript adds 456+12= 468

I know this is very simple code, I am not familiar with Javascript programming and I pretty much pieced together what I found from searching.

I hope this makes sense, if this is not possible I understand.

Thanks!

Answer 1

using parseInt on the values should help with the math. your results are currently inaccurate because the form values are strings: rather than adding numbers you are concatenating strings.

i changed your ‘number’ input to have an ID attribute, so that you can select with getElementById and replaced the eval call with a call to parseInt.

the value of c in the calculate function needs to be corrected though, not sure what you meant but that will generate an error.

other various HTML tidyness issues (nothing that would break, just easier to read IMHO).

<script type="text/javascript">
function calculate() {
    var a = 12;
    var b = parseInt(document.getElementById("number").value);
    // var c = 5J7S; 
    var d = (a + b + c);
    alert(d);
}
</script>

<form name="form">

Phone: <input type="text" size="3" value=""/>
-
<input type="text" name="number" id="number" size="3" value=""/>
-
<input type="text" size="4" value=""/>

<p>
<input type="button" name="b1" value="Grab Code" onclick="calculate()"> 
</p>
</form>

hope that helps! cheers.