JSFiddle - React, Tailwind, and code Playground

JavaScript

const arr = [
"media-center",
"events",
"current-events",
];

const arr2 = [];

arr.forEach((value, index) => {
  if (index === 0) {
    arr2.push(value);
  } else {
		arr2.push(arr2[index - 1] + '-' + value);
  }
});

console.log(arr2);