Formatting numbers for
Formatting numbers so they confirm to a specific format can be
deceivingly tricky. For example, one of the most common tasks is to format a
number for currency display- an integer followed by two decimals. You may be
tempted to use number rounding to first shift the number's decimal places (via multiplication),round it, then shift the decimal back (via division) to pound the number into your hard earned dollar, though that won't work in many cases. For example, consider the number 120. Number rounding certainly won't get you to 120.00.
To easily format numbers for a specific number of trailing
two nifty methods:
Formats any number for "x" number of trailing
Formats any number so it is of "x" length. Also
The best way to see all the subtleties of toFixed() is to see it in action:
//returns 2489.824 (round up)
//returns 2489.8237000 (padding)
Displaying any number in currency format can't get any easier!
To toPrecision() now:
//returns 123.450 (padding)
//returns 123.5 (round up)
//returns 1.2e+2 (you figure it out!)
toPrecision() is useful if your number must be of a certain length.
What this means is that they'll only work in IE5.5+ and NS6+. The issue of
legacy browsers not performing the desired formatting operation not
withstanding, how do you ensure that these two methods at least degrade well?
Well, by using method detection in your code. For example:
//if browser supports toFixed() method