Floating point number precision in JavaScript

Last Updated : 16 Jan, 2024

The representation of floating points in JavaScript follows the IEEE-754 format. It is a double-precision format where 64 bits are allocated for every floating point.

The displaying of these floating values could be handled using these methods:

Table of Content

Using toFixed() Method
Using toPrecision() Method
Using toExponential() Method

Using toFixed() Method

The number of decimal places in float values can be set using the toFixed() method. This method converts the number into a string, keeping the specified number of digits after the point. If no value is passed as a parameter, then it takes 0 as the default value i.e. no decimal points are displayed.

Syntax:

number.toFixed(digits)

Example: This example shows the use of the toFixed() method.

Javascript

pi = 3.14159265359;
twoPlaces = pi.toFixed(2);
fivePlaces = pi.toFixed(5);
 
console.log(twoPlaces);
console.log(fivePlaces);

Output

3.14
3.14159

Using toPrecision() Method

The number of total digits in float values can be set using the toPrecision() method. This method converts the number into a string, keeping the total number of digits of the value as specified and rounding them to the nearest number. If no value is passed as a parameter, then the function acts as a toString() function effectively returning the value passed as a string.

Syntax:

number.toPrecision(precision);

Example: This example shows the use of the toPrecision() method.

Javascript

pi = 3.14159265359;
twoPlaces = pi.toPrecision(2);
fivePlaces = pi.toPrecision(5);
 
console.log(twoPlaces);
console.log(fivePlaces);

Output

3.1
3.1416

Using toExponential() Method

JavaScript Number toExponential() method is used to convert a number to its exponential form. It returns a string representing the Number object in exponential notation. The toExponential() method is used with a number as shown in the above syntax using the ‘.’ operator. This method will convert a number to its exponential form.

Syntax:

number.toExponential(value)

Example: toExponential(2) represents the number 12345.6789 in exponential notation with 2 digits of precision. The output might look like 1.23e+4, where 1.23 is the significand and 4 is the exponent.

Javascript

const myNumber = 12345.6789;
 
// Using toExponential with precision
const exponentialNotation = myNumber.toExponential(2);
 
console.log(exponentialNotation);

Output

1.23e+4

Binary Representation of Previous Number in JavaScript

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Article Tags :

Floating point number precision in JavaScript

Using toFixed() Method

Syntax:

Javascript

Using toPrecision() Method

Syntax:

Javascript

Using toExponential() Method

Syntax:

Javascript

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