Desafio decimal para binário

convert-dec-bin.js

const getLog2 = (n) => Math.round(Math.log2(n))

const reverseSeq = (n) => Array.from(Array(n + 1).keys()).reverse()

const getPow = (b, n) => Math.pow(b, n)

const decToBin = (n) => {
	reverseSeq(getLog2(n)).reduce(
		(acc, curr) => (getPow(2, curr) <= n) ? ( n -= getPow(2, curr), acc + '1' ) : acc + '0', ''
	)
}

const b = decToBin(257)
console.log(b)

Corrigido:

const getLog2 = (n) => Math.round(Math.log2(n))

const reverseSeq = (n) => Array.from(Array(n + 1).keys()).reverse()

const getPow = (b, n) => Math.pow(b, n)

const decToBin = (n) =>
  reverseSeq(getLog2(n)).reduce(
    (acc, curr) => (getPow(2, curr) <= n) ? ( n -= getPow(2, curr), acc + '1' ) : acc + '0', ''
  )


const b = decToBin(257)
console.log(b)

Melhorei:

const getLog2 = ( n ) => Math.round( Math.log2(n ) )

const reverseSeq = ( n ) => Array.from( Array( n + 1 ).keys() ).reverse()

const getPow = ( b, n ) => Math.pow( b, n )

const toBin = ( n ) => ( acc, curr ) => 
  (getPow(2, curr) <= n) 
    ? ( n -= getPow(2, curr), acc + '1' ) 
    : acc + '0'

const decToBin = (n) =>
  reverseSeq( getLog2( n ) ).reduce( toBin( n ), '' )

const b = decToBin(257)
console.log(b)