Generate a random email based on a given name

generate-email.js

function randomInt(a = 0, b = 0) { return (a + window.crypto.getRandomValues(new Uint32Array(1))[0] % Math.abs(b - a)).toString(); }
String.prototype.nRepeat = function (n) { return '_'.repeat(n).split('').map(x => this.toString()); }
String.prototype.removeVowels = function (n) { return this.toString().replace(/a|e|i|o|u/g,''); }
function toss() { return Boolean(Math.round(Math.random())); }

let domain = '@gmail.com'.nRepeat(7).concat(['@live.com', '@yahoo.com', '@hotmail.com']); // Giving more weight to gmail domains
let names = ['Tony Stark', 'Bruce Wayne', 'Steve Rogers', 'Clark Kent'];

function randomDomain() { return domain[randomInt(0, domain.length)]; }

function genEmail(name) {
  let [fn, ln] = name.split(' ');
  let revrs = toss();                                             // Reverse ID string
  let rmfnv = toss(); fn = rmfnv ? fn.removeVowels() : fn;        // Remove vowels from first name
  let rmlnv = toss(); ln = rmlnv && ln ? ln.removeVowels() : ln;  // Remove vowels from last name
  let numfr = toss() ? randomInt(0, 2000) : null;                 // Insert random number before first name
  let nummd = toss() ? randomInt(0, 2000) : null;                 // Insert random number between first and last name
  let numlt = toss() ? randomInt(0, 2000) : null;                 // Insert random number after last name
  let indot = toss() ? '.' : null;                                // Insert between first and last name
  
  let id = [numfr, fn, indot, nummd, ln, numlt];
  id = revrs ? id.reverse() : id;
  return id.join('').toLowerCase().replace(/^[0-9.]+/,'') + randomDomain();
}

names.forEach(name => console.log(name + ' -> ' + genEmail(name)))

/** Sample Output
  Tony Stark -> tony.stark@gmail.com
  Bruce Wayne -> brucewayne81@gmail.com
  Steve Rogers -> rogers83.stv90@gmail.com
  Clark Kent -> knt213.clark@hotmail.com
*/