Implement a function which extends Array.prototype.
Implement a dropdown component.
Difference between localStorage and cookies.
Merge two sorted integer arrays, remove duplicates.
You have an image on a page, write css and js so that when mouse is over the image, it rotates 180 deg with 1 sec animation.
Given a list of points, find out if any four of them form a square. Return 'true' if possible, else 'false'.
Check for balanced brackets in a string.
Given two nodes, return the section of the tree between these two nodes.
Find the islands in a grid of land and sea.