BigInt in JavaScript: The New Standard for Large Integers

For many years, JavaScript's limitation on integer size posed a problem when working with large numbers. However, ECMAScript 2020 introduced a new data type: BigInt, which allows working with arbitrarily large integers.

This article will discuss:

• What is BigInt?
• How to create and use it
• Differences from the Number type
• Operations with BigInt
• Limitations

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What is BigInt?

BigInt is a new primitive type in JavaScript that allows storing integers much larger than what the Number type can handle.

JavaScript's standard Number type is based on the IEEE 754 double-precision floating-point format, which supports values up to Number.MAX_SAFE_INTEGER (2⁵³ - 1, or 9007199254740991). Beyond this, inaccuracies can occur.

    console.log(Number.MAX_SAFE_INTEGER); // 9007199254740991
    console.log(Number.MAX_SAFE_INTEGER + 1); // 9007199254740992
    console.log(Number.MAX_SAFE_INTEGER + 2); // 9007199254740992 😱

Here, we see a loss of precision.

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How to Create a BigInt

There are two primary ways to create BigInt values:

1. Using a literal (appending 'n')

    const big = 1234567890123456789012345678901234567890n;

Simply append n to the end of an integer.

2. Using the BigInt() function

    const big = BigInt("1234567890123456789012345678901234567890");

You can pass a string or a number to the function.

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Operations with BigInt

You can perform basic mathematical operations with BigInt:

    const a = 1234567890123456789012345678901234567890n;
    const b = 987654321098765432109876543210987654321n;
    
    console.log(a + b); // addition
    console.log(a - b); // subtraction
    console.log(a * b); // multiplication
    console.log(a / b); // division (rounds toward zero)
    console.log(a % b); // remainder

Note: BigInt division always rounds toward zero, even when there's a remainder.

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Compatibility Between Number and BigInt

JavaScript does not allow mixing Number and BigInt in the same operation:

    const big = 10n;
    const num = 5;
    
    console.log(big + num); // TypeError

To combine them, you must explicitly convert the types:

    console.log(big + BigInt(num)); 
    console.log(Number(big) + num); 

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BigInt and JSON

Attempting to serialize BigInt with JSON will throw an error:

    JSON.stringify({ value: 123n }); // TypeError

You must first convert it to a String or Number:

    JSON.stringify({ value: String(123n) }); // "{\"value\":\"123\"}"

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Useful Properties

    typeof 123n; // "bigint"

You can compare BigInt and Number (if their values match):

    123n == 123; // true
    123n === 123; // false (different types)

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Limitations

BigInt does not work with certain Web APIs and DOM manipulations (e.g., Canvas, WebGL).

Math methods cannot be used with BigInt:

    Math.sqrt(25n); // TypeError

BigInt cannot have decimal values:

    10.5n; // SyntaxError