Typeerror: do not know how to serialize a bigint

Today, we are going to deal with “typeerror: do not know how to serialize a bigint,” an error message in JavaScript.

If this error message gives you a hard time, well, we’ve got you back!

In this article, we’ll explore the solutions to fix this error.

But before we proceed to the solutions, we must first understand what this error means and why it occurs.

So let’s get started.

What is BigInt JavaScript?

“BigInt” is a numeric data type in JavaScript that can represent integers with arbitrary precision.

In addition to that, “BigInt” is created by appending “n” to the end of an integer literal or by calling the BigInt() function and giving it an integer value or string value as an argument.

Moreover, with “BigInt” you can safely store and hold a larger integer value than a regular integer.

What is “typeerror: do not know how to serialize a bigint”?

The “typeerror: do not know how to serialize a bigint” occurs when you are trying to serialize a BigInt using JSON.stringify().

However, JSON.stringify() does not know how to serialize BigInt values by default.

One way to work around this problem is by converting BigInt to a string.

What is serialization?

Serialization is the process of converting a data structures or object into a series of bytes that saves the state of the object in an easily transmittable form.

This allows the data to be delivered to another data store, application, or some other destination.

Why does this “do not know how to serialize a bigint” error occurs?

This error occurs due to various reasons, such as:

→ When you are using an outdated or incompatible libraries and it may not support the serialization of bigint objects.

→ When data type that is being serialized is not is not a “bigint” object certainly, the serialization process may not recognize it as a “bigint” object. 

→ This occurs when the serialization function is called improperly or incorrectly. In short there’s a syntax errors in your code

How to fix “typeerror: do not know how to serialize a bigint”?

To fix this error, convert BigInt to a string before serializing it.

const bigIntValue = 123456789n;
const serialized = JSON.stringify({ value: bigIntValue.toString() });
console.log(serialized); 

By converting the BigInt value to a string using the toString() method before serializing it with JSON.stringify(), it will resolve the error quickly.

Output:

{"value":"123456789"}

Here are the additional solutions you can use to fix this “do not know how to serialize a bigint” type error in JavaScript:

1: Use a custom replacer function with JSON.stringify()

You can use custom replacer function with JSON.stringify() to handle BigInt values.

The replacer function is called for each value being serialized and can return a modified value to be serialized.

const bigIntValue = 123456789n;
const serialized = JSON.stringify(bigIntValue, (_, value) => typeof value === 'bigint' ? value.toString() + 'n' : value);
console.log(serialized);

Output:

"123456789n"

2: Store the BigInt value in an object with a custom toJSON() method:

You can store the BigInt value in an object with a custom toJSON() method. 

The toJSON() method is called by JSON.stringify() when serializing the object.

class BigIntWrapper {
    constructor(value) {
        this.value = value;
    }
    toJSON() {
        return this.value.toString() + 'n';
    }
}
const bigIntValue = new BigIntWrapper(123456789n);
const serialized = JSON.stringify(bigIntValue);
console.log(serialized);

Output:

"123456789n"

3: Use a third-party library that supports serializing BigInt values

Alternatively, you can use a third-party library that supports serializing BigInt values.

Here we BSON library to serialize an object containing a BigInt value.

const BSON = require('bson');
const bigIntValue = 1234567890n;
const serialized = BSON.serialize({ value: bigIntValue });
console.log(serialized.toString('hex')); 

Output:

"123456789n"

Conclusion

In conclusion, the “typeerror: do not know how to serialize a bigint” occurs when you are trying to serialize a BigInt using JSON.stringify().

This article already provides several solutions above so that you can fix the “do not know how to serialize a bigint” error message in JavaScript.

We are hoping that this article provided you with sufficient solutions to get rid of the error.

You could also check out other “typeerror” articles that may help you in the future if you encounter them.

• Typeerror: argument of type ‘builtin_function_or_method’ is not iterable
• Typeerror: ‘bool’ object is not subscriptable
• Typeerror: ‘bool’ object is not iterable

Caren Bautista

Technical Writer at PIES IT Solution

Responsible for crafting clear, well-structured, and beginner-friendly content across the platform. Handles the writing, proofreading, and editorial review of tutorials, guides, and documentation to ensure every article is accurate, readable, and easy to follow.

Expertise: Technical Writing · Content Creation · Documentation · Editorial Writing · JavaScript · TypeScript · Python · Python Errors · HTTP Errors · MS Excel  · View all posts by Caren Bautista →