btoa.js

function btoa(v) {
  var l=v.length,i=(~~(l/3)+1)*4,n,c='',r='',e=0,s,t,q,h='ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
  while(--i){
    if(l-->0){
      n=v[v.length-1-l].charCodeAt().toString(2)
      c=c+('00000000'.substr(n.length)+n)
    }
    s=c.substr(e,6)
    r=r+h[parseInt(s,2)]
    e=e+6
  }
  t=s.length
  q=t<8?t<7?'=':'':'=='
  return r+q
}



function btoa2(v){
  for(var e=v.length,i=(~~(e/3)+1)*4;e;--e) {
    console.log(e)
  }
  // return r
}




var wikipedia = 'Man is distinguished, not only by his reason, but by this singular passion from other animals, which is a lust of the mind, that by a perseverance of delight in the continued and indefatigable generation of knowledge, exceeds the short vehemence of any carnal pleasure.'

// var b = btoa(wikipedia)
var b = btoa2(wikipedia)

console.log(b)