number.toExponential

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

Syntax

numObj.toExponential([fractionDigits])

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.

Return value

A string representing the given Number object in exponential notation with one digit before the decimal point, rounded to fractionDigits digits after the decimal point.

Exceptions

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.

Description

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 whitespace(s) 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().

Examples

Using toExponential

var numObj = 77.1234;

console.log(numObj.toExponential());  // logs 7.71234e+1
console.log(numObj.toExponential(4)); // logs 7.7123e+1
console.log(numObj.toExponential(2)); // logs 7.71e+1
console.log(77.1234.toExponential()); // logs 7.71234e+1
console.log(77 .toExponential());     // logs 7.7e+1

Specifications

Specification	Status	Comment
ECMAScript 3rd Edition (ECMA-262)	Standard	Initial definition. Implemented in JavaScript 1.5.
ECMAScript 5.1 (ECMA-262) The definition of 'Number.prototype.toExponential' in that specification.	Standard
ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'Number.prototype.toExponential' in that specification.	Standard
ECMAScript 2017 Draft (ECMA-262) The definition of 'Number.prototype.toExponential' in that specification.	Draft

Browser compatibility

See also

• Number.prototype.toFixed()
• Number.prototype.toPrecision()
• Number.prototype.toString()