array1.concat(array2, array3, ..., arrayX)

import React from 'react';

export default function ArrayConcat() {
  const arr1 = ["Cecilie", "lone"];
  const arr2 = ["Emil", "Tobias", "Linus"];
  const children = arr1.concat(arr2);

  return (
    <div>
      <h2>Children:</h2>
      <ul>
        {children.map((child, index) => (
          <li key={index}>{child}</li>
        ))} 
      </ul>
    </div>
  );  
}