The toPrecision()
method returns a string representing the Number
object to the specified precision.
Syntax
numObj.toPrecision([precision])
Parameters
precision
Optional- 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
- If
precision
is not between1
and100
(inclusive), aRangeError
is thrown. Implementations are allowed to support larger and smaller values as well. ECMA-262 only requires a precision of up to 21 significant digits.
Examples
Using toPrecision
let numObj = 5.123456 console.log(numObj.toPrecision()) // logs '5.123456' console.log(numObj.toPrecision(5)) // logs '5.1235' console.log(numObj.toPrecision(2)) // logs '5.1' console.log(numObj.toPrecision(1)) // logs '5' numObj = 0.000123 console.log(numObj.toPrecision()) // logs '0.000123' console.log(numObj.toPrecision(5)) // logs '0.00012300' console.log(numObj.toPrecision(2)) // logs '0.00012' console.log(numObj.toPrecision(1)) // logs '0.0001' // note that exponential notation might be returned in some circumstances console.log((1234.5).toPrecision(2)) // logs '1.2e+3'
Specifications
Specification |
---|
ECMAScript (ECMA-262) The definition of 'Number.prototype.toPrecision' in that specification. |
Browser compatibility
The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Desktop | Mobile | Server | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
toPrecision | Chrome Full support 1 | Edge Full support 12 | Firefox Full support 1 | IE Full support 5.5 | Opera Full support 7 | Safari Full support 2 | WebView Android Full support 1 | Chrome Android Full support 18 | Firefox Android Full support 4 | Opera Android Full support 10.1 | Safari iOS Full support 1 | Samsung Internet Android Full support 1.0 | nodejs Full support 0.1.100 |
Legend
- Full support
- Full support