const alphabet = `abcdefghijklmnopqrstuvwxyz`;


    const chiffre3 = `b'qljbg go bq wlg

b'qljbg, uglcg fgi qlui, qtgd vqujxo bq wlg,
flhhgugcogi f'kpvgpu, fg bqcjqjg go f'giwulo, go f'kqslo,
ouqtguiqlgco pc sxpo fg wuqlulg.
bg kqiquf bgi qiigvsbg gc pc dxlc fgoxpucg.
b'qjqiig gpo wgpu; vqli b'qljbg, qzqco hxuo slgc flcg,
bq uqiipug, go bpl flo: "qbbxci fg dxvwqjclg ;
il bg vqloug fgi flgpe qiiga ixptgco i'gccplg,
bpl ypl jxptgucg b'pcltgui,
m'gc wpli slgc hqlug qpoqco, vxl yp'xc iqlo ypl bg igui.
gcougogcgavxl fxcd, go iqci dgugvxclg."
dqypgosxcsgd qbxui fg mqigu qp wbpi fup,
ipu dgdl, ipu dgbq, ipu oxpo. b'kxvvg f'kxuqdg,
fliqco bg slgc, bg vqb q ouqtgui dkqvwi, c'gpo ip
dg yp'gc hqlo fg sqslb z iqtqlo cxoug qjqiig.
gbbg xhhug f'qtguolu fg oxpo dg ypl ig wqiig,
iqpoqco, qbbqco fg wbqdg gc wbqdg,
sxc giwlxc, flgp iqlo. ixc xhhug qzqco fgwbp,
b'qljbg bpl flo oxpo gc dxbgug :
"cg yplooga wxlco txoug igmxpu,
dqypgosxcsgd, vqvlg ; qflgp ; mg c'ql ypg hqlug
f'pcg sqslbbqufg q vq dxpu :
d'gio pc hxuo vgdkqco dquqdogug.?
vqujxo cg fgvqcfqlo wqi vlgpe.
dg c'gio wqi dg yp'xc duxlo ypg f'gcougu dkga bgi flgpe :
dgo kxccgpu q ixptgco fg vxuogbbgi qcjxliigi.
ugfligpui, giwlxci, jgci q b'qlu juqdlgpe,
qp dxgpu oxpo flhhgugco, i'z ugcfgco xflgpe,
ypxlypg qlcil ypg bq wlg lb hqlbbg fqci dgi blgpe
wxuogu kqslo fg fgpe wquxliigi.

mgqc fg bq hxcoqlcg, bg hqsbgi`;

  const alphabetArray = alphabet.split('');
  const chiffre3Array = chiffre3.split('');


  let frequenceArray = [];

  for (i = 0; i < chiffre3.length; i++) {
      let lettre = chiffre3[i];
      if (alphabetArray.indexOf(lettre) !== -1) { // Si i est dans alphabet
          console.log()
          if (frequenceArray.indexOf(lettre) !== 1) { // Si i est déjà dans frequence
              frequenceArray[i] += 1;
          } else {
              frequenceArray[i] = 1;
          }
      }
  }
  console.log(frequenceArray);
  frequenceArray = frequenceArray.map(value => value / chiffre3.length);
console.log(frequenceArray);