How Do I Do This?

**Evertjan.** · Jul 23 '05, 09:33 PM

Re: How Do I Do This?

Wayfarer wrote on 20 jul 2005 in comp.lang.javas cript:
[color=blue]
> Can anyone please tell me how to do this correctly? I'm trying
> to learn javascript and I've taken it as far as I can and I'm
> extremely frustrated!
>
> TIA
>
> Neill
>
> var L = prompt("Enter the length of carpet");
> var W = prompt("Enter the width of carpet");
> var C = prompt("Enter the cost per unit");
>
> function carpet_cost(L,W ,C)
> {
> var area = L * W;
> var carpet_cost=(ar ea * C);
> }
> return carpet_cost
>
> window.alert ("The total cost of the carpet is", carpet_cost);[/color]

You should be frustrated. Building a whole project, even this small,
without debugging, doesn't teach you.

try and experiment with this:

=============== =

<script type=text/javascript>

function carpetCostCpute (L,W,C) {
return L * W * C;
}

function carpetCost() {
return carpetCostCpute (
prompt('Enter the length of carpet',''),
prompt('Enter the width of carpet',''),
prompt('Enter the cost per unit','') );
}

i=10
while (i-- >0){
r = carpetCost()
if (r==0)
i=0
else
alert ('The total cost of the carpet is ' + r);
}

</script>

=============== =

--
Evertjan.
The Netherlands.
(Replace all crosses with dots in my emailaddress)

**Dr John Stockton** · Jul 23 '05, 09:34 PM

Re: How Do I Do This?

JRS: In article <MPG.1d481a4f12 00a49c989693@ne ws.highstream.n et>, dated
Wed, 20 Jul 2005 09:23:16, seen in news:comp.lang. javascript, Wayfarer
<wfping2004-miscNO@SPAMyaho o.com> posted :[color=blue]
>Can anyone please tell me how to do this correctly? I'm trying
>to learn javascript and I've taken it as far as I can and I'm
>extremely frustrated![/color]

[color=blue]
> var L = prompt("Enter the length of carpet");
> var W = prompt("Enter the width of carpet");
> var C = prompt("Enter the cost per unit");
>
> function carpet_cost(L,W ,C)
> {
> var area = L * W;
> var carpet_cost=(ar ea * C);
> }
> return carpet_cost
>
> window.alert ("The total cost of the carpet is", carpet_cost);[/color]

(1) Your return statement is after the function and should be within it;
(2) Method .alert takes a single (string) parameter; change the comma to
a plus;
(3) The call of carpet cost in the .alert() needs parentheses and
parameters.

With those changes, this works :

var L = prompt("Enter the length of carpet");
var W = prompt("Enter the width of carpet");
var C = prompt("Enter the cost per unit");

function carpet_cost(L,W ,C)
{
var area = L * W;
var carpet_cost=(ar ea * C);
return carpet_cost
}

window.alert
("The total cost of the carpet is" + carpet_cost(L, W, C));

Now improvements to your coding :
(a) It is confusing to use the same name for a function and a var in it;
change the latter to, say, CC;
(b) It is inappropriate to use the same name for a parameter inside and
outside a function; change the former;
(c) Code should be indented to show structure, and other spaces help;
(d) Parentheses are not needed around the multiplication;
(e) Inputs are essentially Numbers, so it is cleaner to convert to
Number immediately - see FAQ sec. 4.21.

var LoC = + prompt("Enter the length of carpet") ;
var WoC = + prompt("Enter the width of carpet") ;
var CpU = + prompt("Enter the cost per unit area") ;

function carpet_cost(L, W, C) {
var area = L * W ;
var CC = area * C ;
return CC }

window.alert("T he total cost of the carpet is" +
carpet_cost(LoC , WoC, CpU)) ;

The function can be simplified to

function carpet_cost(L,W ,C) { return L * W * C }

Given typical widths, lengths, and prices, you should need to display in
customary currency format - see FAQ, sec 4.6.

Inputs should be validated as being numbers of reasonable format - see
<URL:http://www.merlyn.demo n.co.uk/js-valid.htm>.

It would be better to use a form with <input type=text ...> for
input and output, and a button for calculation.

--
© John Stockton, Surrey, UK. ?@merlyn.demon. co.uk Turnpike v4.00 IE 4 ©
<URL:http://www.jibbering.c om/faq/> JL/RC: FAQ of news:comp.lang. javascript
<URL:http://www.merlyn.demo n.co.uk/js-index.htm> jscr maths, dates, sources.
<URL:http://www.merlyn.demo n.co.uk/> TP/BP/Delphi/jscr/&c, FAQ items, links.

How Do I Do This?

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