The toPrecision() method of Number values returns a string representing this number to the specified precision.

Syntax

toPrecision()
toPrecision(precision)

Parameters

• precision

  • : An integer specifying the number of significant digits.

Return value

A string representing a Number object in fixed-point or exponential notation rounded to precision significant digits. See the discussion of rounding in the description of the Number.prototype.toFixed method, which also applies to toPrecision().

If the precision argument is omitted, behaves as Number.prototype.toString. If the precision argument is a non-integer value, it is rounded to the nearest integer.

Exceptions

• RangeError
  • : Thrown if precision is not between 1 and 100 (inclusive).

Examples

Using toPrecision

let num = 5.123456;

console.log(num.toPrecision()); // '5.123456'
console.log(num.toPrecision(5)); // '5.1235'
console.log(num.toPrecision(2)); // '5.1'
console.log(num.toPrecision(1)); // '5'

num = 0.000123;

console.log(num.toPrecision()); // '0.000123'
console.log(num.toPrecision(5)); // '0.00012300'
console.log(num.toPrecision(2)); // '0.00012'
console.log(num.toPrecision(1)); // '0.0001'

// note that exponential notation might be returned in some circumstances
console.log((1234.5).toPrecision(2)); // '1.2e+3'

Specifications

Browser compatibility

See also

• Number.prototype.toFixed
• Number.prototype.toExponential
• Number.prototype.toString