Editor's note: We asked Joey Lott, the author of ActionScript Cookbook, to select some recipes from his book to showcase here on the Web DevCenter. He came up with quite a diverse slate. Today, you'll find recipes that deal with currency formatting, how to use a unique depth when creating a new movie clip, and how to perform actions at set intervals as well as create a clock showing the absolute time. Next Friday, we'll conclude this series with recipes on pausing and resuming a sound, saving a local shared object, and searching XML. This diversity of offerings reflects the sheer volume of solutions to common ActionScript problems that you'll find in Joey's book.

Recipe 5.6: Formatting Currency Amounts

Problem

You want to format a number as currency, such as dollars.

Solution

Create a custom Math.currencyFormat( ) method.

Discussion

Unlike some other languages, such as ColdFusion, ActionScript does not have a
built-in function for formatting numbers as currency amounts. That's the bad
news. The good news is that it is not too difficult to create a custom method to
format numbers as currency amounts.

Our custom Math.currencyFormat( ) method accepts up to seven parameters:

num
The number to format.

decimalPl
The number of decimal places in the formatted number.

currencySymbol
The symbol, such as a dollar sign ($), to use.

thousandsDelim
The characters used to delimit thousands, millions, etc.

decimalDelim
The characters used to delimit the fractional portion from the whole number.

truncate
If true, truncate the number to the specified number of decimal places; otherwise, round the number.

spaceFill
The number of spaces the entire formatted string should occupy.

Here is our custom Math.currencyFormat( ) method. The method converts a numeric parameter into a currency-formatted string. Include this method within Math.as along with the custom roundDecPl( ), numberFormat( ), and zeroFill( ) methods in this chapter, on which this
example relies.

Math.currencyFormat = function (num, decimalPl, currencySymbol, thousandsDelim,
decimalDelim, truncate, spaceFill) {
// Default to two decimal places, a dollar sign ($), a comma for thousands,
// and a period for the decimal point. We implemented the defaults using
// the conditional operator. Compare with Recipe 5.5.
decimalPl = (decimalPl == undefined) ? 2 : decimalPl;
currencySymbol = (currencySymbol == undefined) ? "$" : currencySymbol;
thousandsDelim = (thousandsDelim == undefined) ? "," : thousandsDelim;
decimalDelim = (decimalDelim == undefined) ? "." : decimalDelim;
// Split the number into the whole and decimal (fractional) portions.
var parts = String(num).split(".");
// Truncate or round the decimal portion, as directed.
if (truncate) {
parts[1] = Number(parts[1]) * Math.pow(10, -(decimalPl - 1));
parts[1] = String(Math.floor(parts[1]));
} else {
// Requires the roundDecPl( ) method defined in Recipe 5.3
parts[1] = Math.roundDecPl(Number("." + parts[1]), decimalPl);
parts[1] = String(parts[1]).split(".")[1];
}
// Ensure that the decimal portion has the number of digits indicated.
// Requires the zeroFill( ) method defined in Recipe 5.4.
parts[1] = Math.zeroFill(parts[1], decimalPl, true);
// If necessary, use the numberFormat( ) method from Recipe 5.5 to
// format the number with the proper thousands delimiter and leading spaces.
if (thousandsDelim != "" || spaceFill != undefined) {
parts[0] = Math.numberFormat(parts[0], thousandsDelim, "",
spaceFill - decimalPl - currencySymbol.length);
}
// Add a currency symbol and use String.join( ) to merge the whole (dollar)
// and decimal (cents) portions using the designated decimal delimiter.
return currencySymbol + parts.join(decimalDelim);
};

Here are a few examples of Math.currencyFormat ( ) in action:

Recipe 5.3 and Recipe 5.5. See Appendix A for creating special characters,
including the euro, yen, and British pound symbols. To align currency amounts in
text fields, use a monospaced font and set the field's format to right
justification using the TextFormat.align property.