<button (click)="appendDataToLink()">

test = [
   { name: 'karthik', id: 1, link: '/abc/def/ghi' },
   { name: 'shahbaz', id: 2, link: '/jkl/mno/pqr'}
]

generateRandomNumber() {
   return Math.floor(Math.random() * 10);
}
appendDataToLink() {
  this.test.forEach( e => {
     e.link = `${e.link}/rd-${this.generateRandomNumber()}`
  });
  console.log(this.test);
}