Cross-Site Request Forgery (CSRF) is a type of attack that causes an authorized user to do undesirable activities on a web application. An attacker can deceive users of a web application into doing activities of the attacker's choosing using social engineering techniques.

There is a traversal API that allows us to find structurally related elements of the document; it treats a document as a tree of element objects. We can access these traversal API by referring to a specific element's parent, children, and siblings properties.

We can use client-side JavaScript's event API to define and dispatch our events using CustomEvent. Assume our application needs to conduct a long computation or a network request on a regular basis, and the other functionality or user interface is unavailable while these operations are in progress.

Given the root of a binary tree, check whether it is a mirror of itself (i.e., symmetric around its center).

Given the head of a singly linked list, return true if it is a palindrome.

Given an integer array nums, move all 0's to the end of it while maintaining the relative order of the non-zero elements. Note that you must do this in-place without making a copy of the array.

A message containing letters from A-Z can be encoded into numbers using the mapping. To decode an encoded message, all the digits must be grouped then mapped back into letters using the reverse of the mapping above (there may be multiple ways).

Given an m x n 2D binary grid, grid which represents a map of '1's (land) and '0's (water), return the number of islands.

A stack is an abstract data type that stores an ordered collection of items which follow first in last out (FILO) or last in first out (LIFO) principle; with two principal operations: push, which adds an item to the stack, and pop, which removes the most recently added item.

Dijkstra's algorithm is an algorithm for finding the shortest paths between nodes in a graph, which may represent, for example, road networks. It was conceived by computer scientist Edsger W. Dijkstra in 1956 and published three years later. The algorithm exists in many variants.

Autocomplete or suggestion or typeahead offers a number of possible values while typing. I am going to solve this problem using trie data structure and algorithm.

Web Worker API is a JavaScript web API for running multiple tasks simultaneously without affecting the performance of the apps.

The Beacon API is a JavaScript web API for sending data from the browser to the web server without expecting to get a response. It is used to send analytics, diagnostics, and logging data which doesn't need a response.

On a 2-dimensional grid, there are 4 types of squares. Return the number of 4-directional walks from the starting square to the ending square, that walk over every non-obstacle square exactly once.

Given n non-negative integers representing the histogram's bar height where the width of each bar is 1, find the area of largest rectangle in the histogram.