A BIP68 relative lock-time encoding library.
let bip68 = require('bip68')
bip68.encode({ seconds: 2048 })
// => 0x00400004
bip68.encode({ seconds: 102 })
// => TypeError: Expected Number seconds as a multiple of 512 (as per the BIP)
bip68.encode({ blocks: 54 })
// => 0x00000036
bip68.encode({ blocks: 200 })
// => 0x000000c8
bip68.decode(0x03ffffff)
// => { seconds: 33553920 }
bip68.decode(0x0100fffe) // safely ignores extension bits
// => { blocks: 65534 }
bip68.decode(0xffffffff) // final sequence
// => {}