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JS Numbers

The isSafeInteger() Method

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

Otherwise it returns false.

document.getElementById("demo").innerHTML =
Number.isSafeInteger(10) + "<br>" + Number.isSafeInteger(12345678901234567890);

• Safe integers are all integers from -(2⁵³ - 1) to +(2⁵³ - 1).
• This is safe: 9007199254740991. This is not safe: 9007199254740992.