Number.prototype.toFixed()

The toFixed() method of Number values formats this number using fixed-point notation.

Syntax

toFixed()
toFixed(digits)

Parameters

digits
- : The number of digits to appear after the decimal point; should be a value between 0 and 100, inclusive. If this argument is omitted, it is treated as 0.

Return value

A string representing the given number using fixed-point notation.

Exceptions

RangeError
- : Thrown if digits is not between 0 and 100 (inclusive).
TypeError
- : Thrown if this method is invoked on an object that is not a Number.

Description

The toFixed() method returns a string representation of numObj that does not use exponential notation and has exactly digits digits after the decimal place. The number is rounded if necessary, and the fractional part is padded with zeros if necessary so that it has the specified length.

If the absolute value of numObj is greater or equal to 10²¹, this method uses the same algorithm as Number.prototype.toString and returns a string in exponential notation. toFixed() returns "Infinity", "NaN", or "-Infinity" if the value of numObj is non-finite.

The output of toFixed() may be more precise than toString() for some values, because toString() only prints enough significant digits to distinguish the number from adjacent number values. For example:

(1000000000000000128).toString(); // '1000000000000000100'
(1000000000000000128).toFixed(0); // '1000000000000000128'

However, choosing a digits precision that's too high can return unexpected results, because decimal fractional numbers cannot be represented precisely in floating point. For example:

(0.3).toFixed(50); // '0.29999999999999998889776975374843459576368331909180'

Examples

Using toFixed()

const numObj = 12345.6789;

numObj.toFixed(); // '12346'; rounding, no fractional part
numObj.toFixed(1); // '12345.7'; it rounds up
numObj.toFixed(6); // '12345.678900'; additional zeros
(1.23e20).toFixed(2); // '123000000000000000000.00'
(1.23e-10).toFixed(2); // '0.00'
(2.34).toFixed(1); // '2.3'
(2.35).toFixed(1); // '2.4'; it rounds up
(2.55).toFixed(1); // '2.5'
// it rounds down as it can't be represented exactly by a float and the
// closest representable float is lower
(2.449999999999999999).toFixed(1); // '2.5'
// it rounds up as it's less than Number.EPSILON away from 2.45.
// This literal actually encodes the same number value as 2.45

(6.02 * 10 ** 23).toFixed(50); // 6.019999999999999e+23; large numbers still use exponential notation

Using toFixed() with negative numbers

Because member access has higher precedence than unary minus, you need to group the negative number expression to get a string.

-2.34.toFixed(1); // -2.3, a number
(-2.34).toFixed(1); // '-2.3'