let arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

function someFunc(arr) {
  [arr[0], arr[arr.length - 1]] = [arr[arr.length - 1], arr[0]]
  console.log(arr);
}

someFunc(arr)

import resolve from '@rollup/plugin-node-resolve';
import serve from 'rollup-plugin-serve';
import livereload from 'rollup-plugin-serve';

export default {
  input: './src/main.js',
  output: {
    file: './dist/build.js',
    format: 'esm'
  },
  plugins: [
    resolve(),
    serve('dist'),
    livereload()
  ]
};