The toExponential() method returns a string representing the Number object in exponential notation.

Optional. An integer specifying the number of digits after the decimal point. Defaults to as many digits as necessary to specify the number.

Returns

A string representing a Number object in exponential notation with one digit before the decimal point, rounded to fractionDigits digits after the decimal point. If the fractionDigits argument is omitted, the number of digits after the decimal point defaults to the number of digits necessary to represent the value uniquely.

If you use the toExponential() method for a numeric literal and the numeric literal has no exponent and no decimal point, leave a space before the dot that precedes the method call to prevent the dot from being interpreted as a decimal point.

If a number has more digits than requested by the fractionDigits parameter, the number is rounded to the nearest number represented by fractionDigits digits. See the discussion of rounding in the description of the toFixed() method, which also applies to toExponential().

If fractionDigits is too small or too large. Values between 0 and 20, inclusive, will not cause a RangeError. Implementations are allowed to support larger and smaller values as well.

If this method is invoked on an object that is not a Number.

**Parameters****fractionDigits**Optional. An integer specifying the number of digits after the decimal point. Defaults to as many digits as necessary to specify the number.

Returns

A string representing a Number object in exponential notation with one digit before the decimal point, rounded to fractionDigits digits after the decimal point. If the fractionDigits argument is omitted, the number of digits after the decimal point defaults to the number of digits necessary to represent the value uniquely.

If you use the toExponential() method for a numeric literal and the numeric literal has no exponent and no decimal point, leave a space before the dot that precedes the method call to prevent the dot from being interpreted as a decimal point.

If a number has more digits than requested by the fractionDigits parameter, the number is rounded to the nearest number represented by fractionDigits digits. See the discussion of rounding in the description of the toFixed() method, which also applies to toExponential().

**Throws****RangeError**If fractionDigits is too small or too large. Values between 0 and 20, inclusive, will not cause a RangeError. Implementations are allowed to support larger and smaller values as well.

**TypeError**If this method is invoked on an object that is not a Number.