Number.isSafeInteger() – JavaScript | MDN

By | 2015-07-20
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This is a new technology, part of the ECMAScript 2015 (ES6) standard .This technology’s specification has been finalized, but check the compatibility table for usage and implementation status in various browsers.

 

 

This is a new technology, part of the ECMAScript 2015 (ES6) standard .
This technology’s specification has been finalized, but check the compatibility table for usage and implementation status in various browsers.

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, 253 - 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, 253 is not a safe integer: it can be exactly represented in IEEE-754, but the integer 253 + 1 can’t be directly represented in IEEE-754 but instead rounds to 253 under round-to-nearest and round-to-zero rounding.

The safe integers consist of all integers from -(253 - 1) inclusive to 253 - 1 inclusive.

Syntax

Parameters

testValue
The value to be tested for being a safe integer.

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