Number.isSafeInteger()
The Number.isSafeInteger()
method determines whether the
provided value is a number that is a safe integer.
A safe integer is an integer that
- can be exactly represented as an IEEE-754 double precision number, and
- whose IEEE-754 representation cannot be the result of rounding any other integer to fit the IEEE-754 representation.
For example, 2^53 - 1
is a safe integer: it can be exactly
represented, and no other integer rounds to it under any IEEE-754 rounding mode. In
contrast, 2^53
is not a safe integer: it can be exactly
represented in IEEE-754, but the integer 2^53 + 1
can't be
directly represented in IEEE-754 but instead rounds to 2^53
under
round-to-nearest and round-to-zero rounding. The safe integers consist of all integers
from -(2^53 - 1)
inclusive to 2^53 - 1
inclusive (± 9007199254740991
or ± 9,007,199,254,740,991).
Handling values larger or smaller than ~9 quadrillion with full precision requires using an arbitrary precision arithmetic library. See What Every Programmer Needs to Know about Floating Point Arithmetic for more information on floating point representations of numbers.
For larger integers, consider using the BigInt
type.
Syntax
Number.isSafeInteger(testValue)
Parameters
testValue
-
The value to be tested for being a safe integer.
Return value
The boolean value true
if the given value is a number that is a
safe integer. Otherwise false
.
Polyfill
Number.isSafeInteger = Number.isSafeInteger || function (value) {
return Number.isInteger(value) && Math.abs(value) <= Number.MAX_SAFE_INTEGER;
};
Examples
Using isSafeInteger
Number.isSafeInteger(3); // true
Number.isSafeInteger(Math.pow(2, 53)); // false
Number.isSafeInteger(Math.pow(2, 53) - 1); // true
Number.isSafeInteger(NaN); // false
Number.isSafeInteger(Infinity); // false
Number.isSafeInteger('3'); // false
Number.isSafeInteger(3.1); // false
Number.isSafeInteger(3.0); // true
Specifications
Specification |
---|
ECMAScript Language Specification # sec-number.issafeinteger |
Browser compatibility
BCD tables only load in the browser
See also
- Polyfill of
Number.isSafeInteger
incore-js
- The
Number
object it belongs to. Number.MIN_SAFE_INTEGER
Number.MAX_SAFE_INTEGER
BigInt