Frontend Engineer

The problem can be solved in O(n) time using hashing. Use a hash set to check for the current array value. Check if targetsum – current value exists in the map or not. If it exists, that means a pair with sum equal to target sum exists in the array.

A closure is the combination of a function bundled together (enclosed) with references to its surrounding state (the lexical environment). In other words, a closure gives you access to an outer function’s scope from an inner function. In JavaScript, closures are created every time a function is created, at function creation time.

Shallow Copy: When a reference variable is copied into a new reference variable using the assignment operator, a shallow copy of the referenced object is created. In simple words, a reference variable mainly stores the address of the object it refers to. When a new reference variable is assigned the value of the old reference variable, the address stored in the old reference variable is copied into the new one.

Deep Copy: Deep copy makes a copy of all the members of the old object, allocates separate memory location for the new object and then assigns the copied members to the new object. In this way, both the objects are independent of each other and in case of any modification to either one the other is not affected. Also, if one of the objects is deleted the other still remains in the memory.

Absolute Position: An element with position: absolute; will cause it to adjust its position with respect to its parent. If no parent is present, then it uses the document body as parent.
Syntax : position: absolute;

Fixed Position: Position: fixed; property applied to an element will cause it to always stay in the same place even if the page is scrolled. To position the element we use top, right, bottom, left properties.
Syntax: position: fixed;

The rendering engine has a very important job as it displays what you see on your screen. It communicates with the networking layer of the browser to grab HTML code and other items passed from a remote server. Then it follows these steps:
1. Parsing HTML and creating the DOM Tree – HTML is a hierarchal structure that begins with a tag, usually contains a and tag, and elements can be nested within elements. These HTML elements are parsed and turned into a “DOM tree” by the rendering engine. It is a tree like structure made out of the HTML, where each tag is a branch starting at the root element.
2. Render Tree Construction – CSS attributes (style attributes) are also parsed and combined with the DOM tree to create a “render tree”. This is a tree of visual elements such as height/width and color ordered in the hierarchy in which they are to be displayed in the browser.
3. Layout Process – Once the render tree is constructed, the rendering engine recursively goes through the HTML elements in the tree and figure out where they should be placed on the screen. This starts at the top left in position 0,0 and elements and attributes are mapped to coordinates on the screen.
4. Painting – Each node (branch) of the render tree is drawn out on the screen by communicating with the Operating System Interface which contains designs and styles for how UI elements should look.

Webpack is a static module bundler for JavaScript applications — it takes all the code from your application and makes it usable in a web browser. Modules are reusable chunks of code built from your app’s JavaScript, node_modules, images, and the CSS styles which are packaged to be easily used in your website. Webpack separates the code based on how it is used in your app, and with this modular breakdown of responsibilities, it becomes much easier to manage, debug, verify, and test your code.

Tip 1 : The cross questioning can go intense some time, think before you speak.
Tip 2 : Be open minded and answer whatever you are thinking, in these rounds I feel it is important to have opinion.
Tip 3 : Context of questions can be switched, pay attention to the details. It is okay to ask questions in these round, like what are the projects currently the company is investing, which team you are mentoring. How all is the work environment etc.