Number.prototype.toPrecision()
The toPrecision() method of Number values returns a string representing
this number to the specified precision.
Try it
Syntax
js
toPrecision()
toPrecision(precision)
Parameters
precisionOptional-
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
precisionis not between1and100(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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