Number.prototype.toPrecision()
The toPrecision()
method returns a string representing
the Number
object to the specified precision.
Try it
Syntax
js
toPrecision()
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
-
Thrown if
precision
is not between1
and100
(inclusive).
Examples
Using toPrecision
js
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
Specification |
---|
ECMAScript Language Specification # sec-number.prototype.toprecision |
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