varint

encode whole numbers to an array of protobuf-style varint bytes and also decode them.

var varint = require('varint')

var bytes = varint.encode(300) // === [0xAC, 0x02]
varint.decode(bytes) // 300
varint.decode.bytesRead // 2 (the last decode() call required 2 bytes)

api

varint = require('varint')

varint.encode(num[, output=[], offset=0]) -> array

encodes num into either the array given by offset or a new array at offset and returns that array filled with integers.

varint.decode(data[, offset=0]) -> number

decodes data, which can be either a buffer or array of integers, from position offset or default 0 and returns the decoded original integer.

varint.decode.bytesRead

if you also require the length (number of bytes) that were required to decode the integer you can access it via varint.decode.bytesRead. this is an integer property that will tell you the number of bytes that the last .decode() call had to use to decode.

varint.encode.bytesWritten

similar to bytesRead when encoding a number it can be useful to know how many bytes where written (especially if you pass an output array). you can access this via varint.encode.bytesWritten which holds the number of bytes written in the last encode.

varint.encodingLength(num)

returns the number of bytes this number will be encoded as, up to a maximum of 8.

usage notes

if you are using this to decode buffers from a streaming source it's up to you to make sure that you send 'complete' buffers into varint.decode. the maximum number of bytes that varint will need to decode is 8, so all you have to do is make sure you are sending buffers that are at least 8 bytes long from the point at which you know a varint range begins.

for example, if you are reading buffers from a fs.createReadStream, imagine the first buffer contains one full varint range and half of a second one, and the second buffer contains the second half of the second varint range. in order to be safe across the buffer boundaries you'd just have to make sure the buffer you give to varint.decode contains the full varint range (8 bytes), otherwise you'll get an error.

License

MIT