The Number isSafeInteger() method

Mar 16, 2019

Learn how the JavaScript Number.isSafeInteger() method checks if a value is an integer within the safe range, between -2^53 and 2^53, where precision holds.

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A number might satisfy Number.isInteger() but not Number.isSafeInteger() if it goes out of the boundaries of safe integers, which I explained above.

So, anything over 2^53 and below -2^53 is not safe:

Number.isSafeInteger(Math.pow(2, 53)) // false
Number.isSafeInteger(Math.pow(2, 53) - 1) // true
Number.isSafeInteger(Math.pow(2, 53) + 1) // false
Number.isSafeInteger(-Math.pow(2, 53)) // false
Number.isSafeInteger(-Math.pow(2, 53) - 1) // false
Number.isSafeInteger(-Math.pow(2, 53) + 1) // true

Tagged: JavaScript · All topics

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