Is Safe Integer

The Number.isSafeInteger() Method

A safe integer is an integer that can be exactly represented as a double precision number.

The Number.isSafeInteger() method returns true if the argument is a safe integer.

Example

Number.isSafeInteger(10);    // returns true  
Number.isSafeInteger(12345678901234567890);  // returns false

Safe integers are all integers from

$-(2^{53} - 1)$ to $+(2^{53} - 1)$

This is safe: 9007199254740991

This is not safe: 9007199254740992