A binary gap within a positive integer N is any maximal sequence of consecutive zeros that is surrounded by ones at both ends in the binary representation of N

BinaryGap.js

function BinaryGap(N) {
    //get N binary representation
  let Nbin = N.toString(2);
    //trim from start to last 1
  const lastIndexOfOne = Nbin.lastIndexOf('1')
  Nbin = Nbin.substr(0,lastIndexOfOne);
    //split by 1 
  let Gaps = Nbin.split('1').map(el=> el.length);
    // take max length
    return Math.max(...Gaps); 
}