//const _ = require('lodash');
const fs = require('fs');
fs.readFile('lol.htm', 'utf-8', (err, html) => {
console.log(
//err || _.uniq( html ).join('')
err || Array.from( new Set( html ) ).join('')
);
});
<!DOCTYPEhtml>cas="ngfrieopy:/.WbSdu-8xjv236q1kw497[F]MJ'à,0AB$()
{#;}?&5HIRéVN|zUGXL’ù_ZK©®™ôçè+Q»—«ê%^Ç\û*Ê