|Number.toFixed(x)||Formats any number for "x" number of trailing decimals. The number is rounded up, and "0"s are used after the decimal point if needed to create the desired decimal length.|
|Number.toPrecision(x)||Formats any number so it is of "x" length. Also called significant digits. A decimal point and "0"s are used if needed to create the desired length.|
The best way to see all the subtleties of toFixed() is to see it in action:
var profits=2489.8237 profits.toFixed(3) //returns 2489.824 (round up) profits.toFixed(2) //returns 2489.82 profits.toFixed(7) //returns 2489.8237000 (padding)
Displaying any number in currency format can't get any easier!
To toPrecision() now:
var anumber=123.45 anumber.toPrecision(6) //returns 123.450 (padding) anumber.toPrecision(4) //returns 123.5 (round up) anumber.toPrecision(2) //returns 1.2e+2 (you figure it out!)
toPrecision() is useful if your number must be of a certain length.
var profits=2489.8237 if (profits.toFixed) //if browser supports toFixed() method profits.toFixed(2)
For those of you who also need to ensure legacy browsers such as IE5 also perform the desired number formatting operation, well, then it's time to roll your own function.