myNumber.toExponential( [ fractionDigits ] ) in ECMAScript 262

If fractionDigits is omitted, the number of digits following the decimal point will vary, showing only enough needed to uniquely identify the number.

var precision = [0,1,2,3];
var numbers = [ 0 , 0.567 , 1.5 , -0.07 , 873];
var msg="";
for (var i=0,len=numbers.length;i<len;i++){
    var n = numbers[i];
    msg += "("+n+").toExponential() is '"+n.toExponential()+"'\n";
    for (var j=0,len2=precision.length;j<len2;j++){
        var digits = precision[j];
        msg += "("+n+").toExponential("+digits+") is '"+n.toExponential(digits)+"'\n";
    }
}
/***********************************
msg is
(0).toExponential() is '0e+0'
(0).toExponential(0) is '0e+0'
(0).toExponential(1) is '0.0e+0'
(0).toExponential(2) is '0.00e+0'
(0).toExponential(3) is '0.000e+0'
(0.567).toExponential() is '5.67e-1'
(0.567).toExponential(0) is '6e-1'
(0.567).toExponential(1) is '5.7e-1'
(0.567).toExponential(2) is '5.67e-1'
(0.567).toExponential(3) is '5.670e-1'
(1.5).toExponential() is '1.5e+0'
(1.5).toExponential(0) is '2e+0'
(1.5).toExponential(1) is '1.5e+0'
(1.5).toExponential(2) is '1.50e+0'
(1.5).toExponential(3) is '1.500e+0'
(-0.07).toExponential() is '-7e-2'
(-0.07).toExponential(0) is '-7e-2'
(-0.07).toExponential(1) is '-7.0e-2'
(-0.07).toExponential(2) is '-7.00e-2'
(-0.07).toExponential(3) is '-7.000e-2'
(873).toExponential() is '8.73e+2'
(873).toExponential(0) is '9e+2'
(873).toExponential(1) is '8.7e+2'
(873).toExponential(2) is '8.73e+2'
(873).toExponential(3) is '8.730e+2'
***********************************/