Understanding BigInt in JavaScript

---

In JavaScript, numbers have traditionally been represented using the Number type, which adheres to the IEEE 754 standard for double-precision floating-point arithmetic. This representation, while versatile, has a limitation: it can safely represent integers only up to (2^{53} - 1) (or (9,007,199,254,740,991)). For applications requiring larger integers, JavaScript introduces a solution through the BigInt type.

What is BigInt?

BigInt is a built-in object in JavaScript that provides a way to represent whole numbers larger than those that can be handled by the Number type. Unlike Number, which is suitable for floating-point arithmetic and can handle values between approximately (-1.8 times 10^{308}) and (1.8 times 10^{308}), BigInt is designed specifically for arbitrary-precision integer arithmetic.

Creating BigInt Values

There are a couple of ways to create BigInt values:

1. Using the BigInt Constructor:

const bigIntValue = BigInt(123456789012345678901234567890);

Note that BigInt accepts strings and numbers, but when using numbers, they should be within the range of a Number type.

1. Using the BigInt Literal: BigInt literals are suffixed with an n:

const bigIntLiteral = 123456789012345678901234567890n;

This is a more concise way to define BigInt values directly.

Operations with BigInt

BigInt supports most of the standard arithmetic operators. Here’s a brief overview:

• Addition (+)

const a = 10n;
const b = 20n;
const sum = a + b; // 30n

• Subtraction (-)

const difference = b - a; // 10n

• Multiplication (*)

const product = a * b; // 200n

• Division (/)

const quotient = b / 3n; // 6n (Note: Division results in a `BigInt` which is truncated towards zero)

• Modulus (%)

const remainder = b % 3n; // 2n

• Exponentiation (``)**

const power = a ** 3n; // 1000n

Comparisons and Equality

BigInt can be compared using the standard comparison operators. Note that BigInt values and Number values are not directly comparable:

const a = 10n;
const b = 10;
console.log(a == b); // false
console.log(a === BigInt(b)); // true

Converting Between BigInt and Number

Conversion between BigInt and Number can be done using explicit conversion methods:

• From BigInt to Number:

const bigIntValue = 123n;
const numberValue = Number(bigIntValue);

Note: This can lose precision if the BigInt value is too large.

• From Number to BigInt:

const numberValue = 123;
const bigIntValue = BigInt(numberValue);

Limitations and Considerations

1. Mixed Operations: You cannot mix BigInt and Number in arithmetic operations without explicit conversion:

const a = 10n;
const b = 5;
// The following line will throw a TypeError
const result = a + b;

1. JSON Support: BigInt is not supported in JSON serialization directly. Attempting to stringify BigInt values will result in a TypeError:

const bigIntValue = 123n;
JSON.stringify(bigIntValue); // Throws TypeError

To handle BigInt in JSON, you may need to convert it to a string first:

const bigIntValue = 123n;
const jsonString = JSON.stringify({ value: bigIntValue.toString() });

1. Performance: While BigInt offers arbitrary precision, it can be slower compared to Number operations due to the complexity of handling larger integers.

Use Cases

BigInt is particularly useful in scenarios where precision with large integers is crucial, such as:

• Cryptography
• Large-scale computations (e.g., financial applications)
• High-precision arithmetic in scientific calculations

Conclusion

BigInt is a powerful addition to JavaScript, expanding its capabilities for handling integers beyond the limits of the Number type. Understanding its operations, limitations, and appropriate use cases can help in leveraging its benefits for applications requiring large integer calculations.

---

The above is the detailed content of Understanding BigInt in JavaScript. For more information, please follow other related articles on the PHP Chinese website!