var invertTree = function(root) {
    const reverseNode = node => {
        if (node == null) {
            return null
        }
        reverseNode(node.left);
        reverseNode(node.right);
        let holdLeft = node.left;
        node.left = node.right;
        node.right = holdLeft;
        return node;
    }

    return reverseNode(root);
};

const arithmeticProgression  = (n, lim) =>
  Array.from({ length: Math.ceil(lim / n) }, (_, i) => (i + 1) * n );
  
arithmeticProgression(5, 25); // [5, 10, 15, 20, 25]

const linearSearch = (arr, item) => {
  for (const i in arr) {
    if (arr[i] === item) return +i;
  }
  return -1;
};

linearSearch([2, 9, 9], 9); // 1
linearSearch([2, 9, 9], 7); // -1

<div className="md:self-start sticky top-16 bg-background px-4 mt-1 sm:px-6 md:pt-4 lg:pl-8 lg:pr-4">
          <ScrollArea className="whitespace-nowrap">
            <div className="w-max flex md:flex-col gap-1 bg-transparent text-muted-foreground pb-2">
              {menuData.map((section) => (
                <Button
                  key={section.title}
                  onClick={() => handleScrollToSection(section.title)}
                  variant="ghost"
                  size="sm"
                  className={cn(
                    'w-auto md:w-full hover:cursor-pointer relative md:justify-end',
                    activeSection === section.title
                      ? cn(
                          'text-foreground after:absolute after:bottom-[-2px] after:bottom-0 after:w-full after:h-[2px] after:bg-primary',
                          'md:after:right-[-2px] md:after:top-0 md:after:h-full md:after:w-[2px]',
                        )
                      : '',
                  )}
                >
                  {section.title}
                </Button>
              ))}
            </div>
            <ScrollBar orientation="horizontal" />
          </ScrollArea>
        </div>

// `arr` is an array
const clone = arr => arr.slice(0);

// Or
const clone = arr => [...arr];

// Or
const clone = arr => Array.from(arr);

// Or
const clone = arr => arr.map(x => x);

// Or
const clone = arr => JSON.parse(JSON.stringify(arr));

// Or
const clone = arr => arr.concat([]);

const express = require('express')
const app = express()
const port = 3000

app.get('/', (req, res) => {
  res.send('Hello World!')
})

app.listen(port, () => {
  console.log(`Example app listening on port ${port}`)
})