Returns the shortest string that correctly represent the input number.
All doubles in the range 10^-6 (inclusive) to 10^21 (exclusive)
are converted to their decimal representation with at least one digit
after the decimal point. For all other doubles,
except for special values like NaN or Infinity, this method returns an
exponential representation (see toStringAsExponential).
Returns "NaN" for double.NAN, "Infinity" for double.INFINITY, and
"-Infinity" for double.NEGATIVE_INFINITY.
An int is converted to a decimal representation with no decimal point.
Examples:
(0.000001).toString(); // "0.000001"
(0.0000001).toString(); // "1e-7"
(111111111111111111111.0).toString(); // "111111111111111110000.0"
(100000000000000000000.0).toString(); // "100000000000000000000.0"
(1000000000000000000000.0).toString(); // "1e+21"
(1111111111111111111111.0).toString(); // "1.1111111111111111e+21"
1.toString(); // "1"
111111111111111111111.toString(); // "111111111111111110000"
100000000000000000000.toString(); // "100000000000000000000"
1000000000000000000000.toString(); // "1000000000000000000000"
1111111111111111111111.toString(); // "1111111111111111111111"
1.234e5.toString(); // 123400
1234.5e6.toString(); // 1234500000
12.345e67.toString(); // 1.2345e+68
Note: the conversion may round the output if the returned string
is accurate enough to uniquely identify the input-number.
For example the most precise representation of the double 9e59 equals
"899999999999999918767229449717619953810131273674690656206848", but
this method returns the shorter (but still uniquely identifying) "9e59".
Source
String toString();