Javascript Change Digits

[matthewamzn]

I'm using a javascript to automatically change kilometers to miles, on my website. The only problem is it produces some very awkward looking numbers with many decimal points. Is there a way to make the product a nice round number?

<script language="JavaScript" type="text/javascript">
var prod = ('##miles##' * 1.609344);
document.write(prod, " kms");
</script>

[johnl]

hi,
insert

prod=Math.round(prod*100)/100

as the third line in your script.

[mrhoo]

johnl's code is fine for a round number, but if you want to include a fixed # of decimal places you can use
toFixed():
(number).toFixed(2)

[matthewamzn]

That worked great. Is there a code to deliminate 1000's with a comma?

ie 1,225,365 istead of 1225365

[Bernard Marx]

A: 1225365.4567
B: 1225365

Apply toFixed(2), then split on the decimal point..

A: ["1225365","46"]
B: ["1225365"]

Take the first element, split into chars..

[1,2,2,5,3,6,5]

reverse, join..

"5635221"

replace every full group of 3 digits with itself plus a comma

"563,522,1"

split into chars, reverse, join,
then, if there is a 2nd element in the decimal point split,
add that after a point.

A: "1,225,365.46"
B: "1,225,365"

---

Number.prototype.fullFormat = function(decPlaces)
{
    var parts = this.toFixed(decPlaces).split(".");
    return (
        parts[0].split("").reverse().join("").replace(/\d{3}/g,"$&,")
        .split("").reverse().join("") + (parts[1]?"."+parts[1]:"")
    );
}
alert( (1225365.4567).fullFormat(2) ) /* A */
alert( (-1225365.4567).fullFormat(0) ) /* B */

[Bernard Marx]

You could forget the above. If you are dealing with money (ie want 2 decimal places)then you can simply use the toLocaleString method:

alert( (1234567.34567).toLocaleString() )

[matthewamzn]

How can I combine the script above with mine?

Number.prototype.fullFormat = function(decPlaces)
{
var parts = this.toFixed(decPlaces).split(".");
return (
parts[0].split("").reverse().join("").replace(/\d{3}/g,"$&,")
.split("").reverse().join("") + (parts[1]?"."+parts[1]:"")
);
}

alert( (1225365.4567).fullFormat(2) ) /* A */
alert( (-1225365.4567).fullFormat(0) ) /* B */

<script language="JavaScript" type="text/javascript">
var prod = ('##miles##' * 1.609344);
prod=Math.round(prod*1)/1
document.write(prod, " kms");
</script>

[Bernard Marx]

The script isn't making Javascript sense at the moment.

var milesToKm = 1.609344;
var miles = 15000; /* test value */
document.write( (miles*milesToKm).fullFormat(0)+" km" );
/* or without need for fullFormat */
document.write( (miles*milesToKm).toLocaleString().replace(/[\.,][\d]+$/,'') +" km" )

---

/[\.,][\d]+$/

From right to left..

$ End of string

[/d]+

One or more digits

[\.,]

Dot or comma (allows for "foreign" formats)

Replace this with an empty string, and we have effectively rounded to the nearest unit, but keeping the 1000 separators.