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Number.isSafeInteger()

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20159

Number.isSafeInteger()

function warn(x) {
  if (Number.isSafeInteger(x)) {
    return "Precision safe.";
  }
  return "Precision may be lost!";
}

console.log(warn(Math.pow(2, 53)));
// : "Precision may be lost!"

console.log(warn(Math.pow(2, 53) - 1));
// : "Precision safe."

js
Number.isSafeInteger(testValue)

testValue

true false

-(253 - 1) 253 - 1 (9,007,199,254,740,991)

  • IEEE-754
  • IEEE-754 IEEE-754

253 - 1 IEEE-754 253 IEEE-754 253 + 1 IEEE-754 253

~9 What Every Programmer Needs to Know about Floating Point Arithmetic s

BigInt

isSafeInteger()

js
Number.isSafeInteger(3); // true
Number.isSafeInteger(2 ** 53); // false
Number.isSafeInteger(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

ECMAScript 2027 LanguageSpecification
# sec-number.issafeinteger


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