JavaScript 1.5; JScript 5.5, ECMAScript v3
An implementation-dependent string representation of the number, formatted according to local conventions, which may affect such things as the punctuation characters used for the decimal point and the thousands separator.
TypeError
If this method is invoked on an object that is not a Number.
Number.toExponential( ), Number.toFixed( ), Number.toPrecision( ), Number.toString( )