What's the Highest Integer JavaScript Can Represent Without Losing Precision?

JavaScript's Highest Integer Value Without Precision Loss

JavaScript's capacity to represent integers is bounded by the representation of numbers in the language.

Number Type

The ubiquitous Number type in JavaScript is a 64-bit floating-point number based on IEEE 754. The largest exact integral value this type can represent without precision loss is Number.MAX_SAFE_INTEGER.

2<sup>53</sup> - 1 = 9,007,199,254,740,991

BigInt Type

For integers larger than Number.MAX_SAFE_INTEGER, JavaScript provides the BigInt type, which holds no upper bound.

Bitwise Operators

Note that bitwise operators and shift operators operate on 32-bit integers, resulting in a different maximum safe integer:

2<sup>31</sup> - 1 = 2,147,483,647

Comparison

Safe integers (those below Number.MAX_SAFE_INTEGER) can be correctly compared using equality operators:

const x = 9007199254740992;
const y = -x;

console.log(x == x + 1); // true
console.log(y == y - 1); // true

However, comparisons of integers greater than Number.MAX_SAFE_INTEGER may produce unexpected results.

Key Takeaway

For accurate representation and comparison of large integers, use BigInt. For smaller integers, the Number type is sufficient, but be aware of the maximum safe integer value for bitwise operations.

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