toPrecision() Method – How to Format Number to Precise Length

toPrecision() formats a number to a precise length of digits and returns the result as a string.

Note

toPrecision() is sometimes written as Number.prototype.toPrecision() because it is a method of the Number object’s prototype property.

Syntax of the toPrecision() Method

toPrecision() accepts only one optional argument. Here is the syntax:

number.toPrecision(totalDigits);

The totalDigits argument specifies the number of digits into which browsers should format the given number. If omitted, browsers will return the number as a string without formatting its length.

Note

• toPrecision() returns a string value.
• toPrecision() does not change the original number.
• Browsers round the returned value if necessary.
• Browsers add extra zeros if necessary to make up the totalDigits.
• The totalDigits argument must be an integer between 1 and 100 inclusive. Otherwise, browsers will throw an Uncaught RangeError.
• The computer returns an exponential notation whenever it does a division operation on the given number.

Examples of the toPrecision() Method

Below are examples of the toPrecision() method.

Format 2703.5941 to precisely five digits

const number = 2703.5941;

number.toPrecision(5);

// The invocation above will return: 2703.6

Try Editing It

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Format 2703.5941 to precisely six digits

const number = 2703.5941;

number.toPrecision(6);

// The invocation above will return: 2703.59

Try Editing It

Format 2703.5941 to precisely four digits

const number = 2703.5941;

number.toPrecision(4);

// The invocation above will return: 2704

Try Editing It

Format 2703.5941 to precisely eleven digits

const number = 2703.5941;

number.toPrecision(11);

// The invocation above will return: 2703.5941000

Try Editing It

The snippet above added extra zeros to make up the totalDigits.

Format 2703.5941 to precisely two digits

const number = 2703.5941;

number.toPrecision(2);

// The invocation above will return: 2.7e+3

Try Editing It

The computer returned an exponential value because it divided the number by 1000.

Format 2703.5941 to precisely one digit

const number = 2703.5941;

number.toPrecision(1);

// The invocation above will return: 3e+3

Try Editing It

The computer returned an exponential value because it divided the number by 1000.

Format 2703.5941 to precisely three digits

const number = 2703.5941;

number.toPrecision(3);

// The invocation above will return: 2.70e+3

Try Editing It

The computer returned an exponential value because it divided the number by 1000.