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O método toExponential() retorna uma string  representando o objeto Number por meio de notação exponencial.




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.


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.


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().


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


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

Browser compatibility

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See also

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 Última atualização por: waltton,