bertjs

A production ready implementation of BERT/ETF in Javascript (inspired by BERT-JS).

Usage

node-repl is installed and functions exported (or not) can be used with node shell.

npm run repl

Decoding

// atom support
"test" === decode([131,100,0,4,116,101,115,116])

// erlang string support
"test" === decode([131,107,0,4,116,101,115,116])

// binary support
Uint8Array(4) [ 116, 101, 115, 116 ] === decode([131,109,0,0,0,4,116,101,115,116])

// list support
[[],[[],[]]] === decode([131,108,0,0,0,2,106,108,0,0,0,2,106,106,106,106])

Encoding

Testing

npm test

Type Mapping

The goal of this implementation is to offer a 1:1 mapping between Erlang terms and Javascript types. A client SHOULD NOT have the possility to create atoms (except for null, true and false) or special terms but a server CAN send atoms or specials terms. In fact, special terms SHOULD raise an exception on the client side, but atoms SHOULD BE converted to String.

erlang term	to	javascript type	comment
ATOM_EXT		String
ATOM_UTF8_EXT		String
SMALL_ATOM_EXT		String
SMALL_ATOM_UTF8_EXT		String
BINARY_EXT		ArrayBuffer
BIT_BINARY_EXT		ArrayBuffer
SMALL_INTEGER_EXT		Number
INTEGER_EXT		Number
LARGE_BIG_EXT		Number
SMALL_BIG_EXT		Number
FLOAT_EXT		Number
NEW_FLOAT_EXT		Number
STRING_EXT		String
LIST_EXT		Array
NIL_EXT		Array
SMALL_TUPLE_EXT		Map
LARGE_TUPLE_EXT		Map
MAP_EXT		Map

javascript type	to	erlang term	comments
Null		ATOM_EXT	encoded as nil
String		STRING_EXT	or binary_ext (depending of the content)
ArrayBuffer		BINARY_EXT	-
Boolean		ATOM_EXT	encoded as true or false
Map		MAP_EXT
Set		LIST_EXT
ArrayBuffer		BINARY_EXT
Array		LIST_EXT
Number		NEW_FLOAT_EXT
Int8		SMALL_INTEGER	when 0 =< Int =< 255
Int16		INTEGER_EXT
Int32		INTEGER_EXT
BigInt		LARGE_BIG_EXT
Float		NEW_FLOAT_EXT
Float32		NEW_FLOAT_EXT
Float64		NEW_FLOAT_EXT

References and Resources

• Null
• Boolean
• Number
• BigInt
• String
• Array
• ArrayBuffer
• Map
• WeakMap
• Set