bson

What is bson?

The bson npm package is a library that allows you to serialize and deserialize data in BSON format. BSON, short for Binary JSON, is a binary-encoded serialization of JSON-like documents. It is designed to be efficient in both storage space and scan-speed. The bson package is commonly used when working with MongoDB, as MongoDB uses BSON as its document storage format.

What are bson's main functionalities?

Serialization

This feature allows you to convert a JavaScript object into a BSON formatted buffer. This is useful for storing and transmitting data in a compact binary form.

{"const BSON = require('bson'); const bson = new BSON(); const doc = { hello: 'world' }; const data = bson.serialize(doc); console.log(data); // <Buffer 16 00 00 00 02 68 65 6c 6c 6f 00 06 00 00 00 77 6f 72 6c 64 00 00>"}

Deserialization

This feature allows you to convert BSON data back into a JavaScript object. This is useful when you need to read data that was stored or transmitted in BSON format.

{"const BSON = require('bson'); const bson = new BSON(); const data = Buffer.from('160000000268656c6c6f0006000000776f726c640000', 'hex'); const doc = bson.deserialize(data); console.log(doc); // { hello: 'world' }"}

Other packages similar to bson

msgpack5

msgpack5 is a package that implements the MessagePack serialization format. MessagePack is an efficient binary serialization format that is similar to BSON but is not tied to MongoDB. It aims to be more compact and faster than JSON.

protobufjs

protobufjs is a package that allows you to serialize and deserialize data using Google's Protocol Buffers. Protocol Buffers are similar to BSON in that they provide a way to encode structured data in an efficient binary format, but they require a predefined schema and are more focused on cross-language compatibility.

cbor

cbor is a package that implements the CBOR (Concise Binary Object Representation) data format. Like BSON, CBOR is a binary format that can serialize and deserialize JavaScript objects. However, CBOR is designed to be more compact and to have a wider range of data types than BSON.

README

BSON parser

BSON is short for Bin­ary JSON and is the bin­ary-en­coded seri­al­iz­a­tion of JSON-like doc­u­ments. You can learn more about it in the specification.

This browser version of the BSON parser is compiled using rollup and the current version is pre-compiled in the dist directory.

This is the default BSON parser, however, there is a C++ Node.js addon version as well that does not support the browser. It can be found at mongod-js/bson-ext.

Usage

To build a new version perform the following operations:

npm install
npm run build

A simple example of how to use BSON in the browser:

<script src="./dist/bson.js"></script>

<script>
  function start() {
    // Get the Long type
    const Long = BSON.Long;

    // Serialize document
    const doc = { long: Long.fromNumber(100) }

    // Serialize a document
    const data = BSON.serialize(doc)
    // De serialize it again
    const doc_2 = BSON.deserialize(data)
  }
</script>

A simple example of how to use BSON in Node.js:

const BSON = require('bson');
const Long = BSON.Long;

const doc = { long: Long.fromNumber(100) };

// Serialize a document
const data = BSON.serialize(doc);
console.log('data:', data);

// Deserialize the resulting Buffer
const doc_2 = BSON.deserialize(data);
console.log('doc_2:', doc_2);

Installation

npm install bson

Documentation

Functions

setInternalBufferSize(size)

Sets the size of the internal serialization buffer.

serialize(object) ⇒ Buffer

Serialize a Javascript object.

serializeWithBufferAndIndex(object, buffer) ⇒ Number

Serialize a Javascript object using a predefined Buffer and index into the buffer, useful when pre-allocating the space for serialization.

deserialize(buffer) ⇒ Object

Deserialize data as BSON.

calculateObjectSize(object) ⇒ Number

Calculate the bson size for a passed in Javascript object.

deserializeStream(data, startIndex, numberOfDocuments, documents, docStartIndex, [options]) ⇒ Number

Deserialize stream data as BSON documents.

setInternalBufferSize(size)

Param	Type	Description
size	number	The desired size for the internal serialization buffer

Sets the size of the internal serialization buffer.

serialize(object)

Param	Type	Default	Description
object	Object		the Javascript object to serialize.
[options.checkKeys]	Boolean		the serializer will check if keys are valid.
[options.serializeFunctions]	Boolean	false	serialize the javascript functions (default:false).
[options.ignoreUndefined]	Boolean	true	ignore undefined fields (default:true).

Serialize a Javascript object.

Returns: Buffer - returns the Buffer object containing the serialized object.

serializeWithBufferAndIndex(object, buffer)

Param	Type	Default	Description
object	Object		the Javascript object to serialize.
buffer	Buffer		the Buffer you pre-allocated to store the serialized BSON object.
[options.checkKeys]	Boolean		the serializer will check if keys are valid.
[options.serializeFunctions]	Boolean	false	serialize the javascript functions (default:false).
[options.ignoreUndefined]	Boolean	true	ignore undefined fields (default:true).
[options.index]	Number		the index in the buffer where we wish to start serializing into.

Serialize a Javascript object using a predefined Buffer and index into the buffer, useful when pre-allocating the space for serialization.

Returns: Number - returns the index pointing to the last written byte in the buffer.

deserialize(buffer)

Param	Type	Default	Description
buffer	Buffer		the buffer containing the serialized set of BSON documents.
[options.evalFunctions]	Object	false	evaluate functions in the BSON document scoped to the object deserialized.
[options.cacheFunctions]	Object	false	cache evaluated functions for reuse.
[options.cacheFunctionsCrc32]	Object	false	use a crc32 code for caching, otherwise use the string of the function.
[options.promoteLongs]	Object	true	when deserializing a Long will fit it into a Number if it's smaller than 53 bits
[options.promoteBuffers]	Object	false	when deserializing a Binary will return it as a node.js Buffer instance.
[options.promoteValues]	Object	false	when deserializing will promote BSON values to their Node.js closest equivalent types.
[options.fieldsAsRaw]	Object		allow to specify if there what fields we wish to return as unserialized raw buffer.
[options.bsonRegExp]	Object	false	return BSON regular expressions as BSONRegExp instances.
[options.allowObjectSmallerThanBufferSize]	boolean	false	allows the buffer to be larger than the parsed BSON object

Deserialize data as BSON.

Returns: Object - returns the deserialized Javascript Object.

calculateObjectSize(object)

Param	Type	Default	Description
object	Object		the Javascript object to calculate the BSON byte size for.
[options.serializeFunctions]	Boolean	false	serialize the javascript functions (default:false).
[options.ignoreUndefined]	Boolean	true	ignore undefined fields (default:true).

Calculate the bson size for a passed in Javascript object.

Returns: Number - returns the number of bytes the BSON object will take up.

deserializeStream(data, startIndex, numberOfDocuments, documents, docStartIndex, [options])

Param	Type	Default	Description
data	Buffer		the buffer containing the serialized set of BSON documents.
startIndex	Number		the start index in the data Buffer where the deserialization is to start.
numberOfDocuments	Number		number of documents to deserialize.
documents	Array		an array where to store the deserialized documents.
docStartIndex	Number		the index in the documents array from where to start inserting documents.
[options]	Object		additional options used for the deserialization.
[options.evalFunctions]	Object	false	evaluate functions in the BSON document scoped to the object deserialized.
[options.cacheFunctions]	Object	false	cache evaluated functions for reuse.
[options.cacheFunctionsCrc32]	Object	false	use a crc32 code for caching, otherwise use the string of the function.
[options.promoteLongs]	Object	true	when deserializing a Long will fit it into a Number if it's smaller than 53 bits
[options.promoteBuffers]	Object	false	when deserializing a Binary will return it as a node.js Buffer instance.
[options.promoteValues]	Object	false	when deserializing will promote BSON values to their Node.js closest equivalent types.
[options.fieldsAsRaw]	Object		allow to specify if there what fields we wish to return as unserialized raw buffer.
[options.bsonRegExp]	Object	false	return BSON regular expressions as BSONRegExp instances.

Deserialize stream data as BSON documents.

Returns: Number - returns the next index in the buffer after deserialization x numbers of documents.

FAQ

Why does undefined get converted to null?

The undefined BSON type has been deprecated for many years, so this library has dropped support for it. Use the ignoreUndefined option (for example, from the driver ) to instead remove undefined keys.

How do I add custom serialization logic?

This library looks for toBSON() functions on every path, and calls the toBSON() function to get the value to serialize.

const BSON = require('bson');

class CustomSerialize {
  toBSON() {
    return 42;
  }
}

const obj = { answer: new CustomSerialize() };
// "{ answer: 42 }"
console.log(BSON.deserialize(BSON.serialize(obj)));