Reg Expression for currency

I need a regular expression to format U.S. currency as 1,215.25 (commas
and decimals)...if it is not already in that format. It should also
allow a '-' sign as the first character for negative numbers. I have
looked in the FAQ and through this group, plus the net and cannot seem
to find the right example.

johkar wrote:

I need a regular expression to format U.S. currency as 1,215.25 (commas
and decimals)...if it is not already in that format. It should also
allow a '-' sign as the first character for negative numbers. I have
looked in the FAQ and through this group, plus the net and cannot seem
to find the right example.

function format(c)
{
if (typeof c != "string")
c = new String(c);
c = parseFloat(c.split(",").join("").
replace(/^\$/, "")).toFixed(2).toString();
var t = /(\d)(\d{3})([\.\,])/;
for (;;)
{
o = c;
c = c.replace(t, "$1,$2$3");
if (o == c)
break;
}
return c;
}
alert(format("$1,456,789.12"));
alert(format("$1,456,789.129"));
alert(format(-167));
alert(format(20.3));

johkar wrote:

I need a regular expression to format U.S. currency as 1,215.25 (commas
and decimals)...if it is not already in that format. It should also
allow a '-' sign as the first character for negative numbers. I have
looked in the FAQ and through this group, plus the net and cannot seem
to find the right example.
function format(c)
{
if (typeof c != "string")

Indent (posted) code with spaces, not tabs.
c = new String(c);
No new String object needs to be created for type conversion.
c = parseFloat(c.split(",").join("").
There is no point in split("...").join("") if you can use replace().
There is no point in removing the format first, and then rebuilding
it, if it is already perfect.
replace(/^\$/, "")).toFixed(2).toString();
There is no point in removing a leading `$' but not including it in
the result again. There is no point in toFixed(2).toString(), since
toFixed(...) already returns a string value.
var t = /(\d)(\d{3})([\.\,])/;
Neither the dot nor the comma character needs to be escaped in a
character class. In fact, escaping a special character in a character
class could have the opposite meaning (it does not have in ECMAScript).
for (;;)
{
o = c;
c = c.replace(t, "$1,$2$3");
if (o == c)
break;
}
return c;
}