Front End Web Developer Interview Preparation Guide

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apply lets you invoke the function with arguments as an array. call requires the parameters to be listed explicitly.

This and that are important to variable scope in JavaScript.

Lazy loading is a design pattern commonly used in computer programming to defer initialization of an object until the point at which it is needed.

Lazy loading is loading code only once user needs it. For Example, there is a button on the page, which shows different layout once user pressed it. So there is no need to load code for that layout on initial page load.

Cross-origin resource sharing (CORS) is a mechanism that allows many resources (e.g., fonts, JavaScript, etc.) on a web page to be requested from another domain outside the domain from which the resource originated. It's a mechanism supported in HTML5 that manages XMLHttpRequest access to a domain different.

CORS adds new HTTP headers that provide access to permitted origin domains. For HTTP methods other than GET (or POST with certain MIME types), the specification mandates that browsers first use an HTTP OPTIONS request header to solicit a list of supported (and available) methods from the server. The actual request can then be submitted. Servers can also notify clients whether "credentials" (including Cookies and HTTP Authentication data) should be sent with requests.

AJAX stands for asynchronous JavaScript and XML and allows applications to send and retrieve data to/from a server asynchronously (in the background) without refreshing the page. For example, your new Gmail messages appear and are marked as new even if you have not refreshed the page.

DOCTYPE is an instruction to the web browser about what version of the markup language the page is written. Its written before the HTML Tag. Doctype declaration refers to a Document Type Definition (DTD).

A GET request is typically used for things like AJAX calls to an API (insignificant changes), whereas a POST request is typically used to store data in a database or submit data via a form (significant changes). GET requests are less secure and can be seen by the user in the URL, whereas POST requests are processed in two steps and are not seen by the user. Therefore, POST requests are more secure.

A collection of data containing both properties and methods. Each element in a document is an object. Using the DOM you can get at each of these elements/objects and do some cool sh*t.

DOCTYPE is an instruction to the web browser about what version of the markup language the page is written. Its written before the HTML Tag. Doctype declaration refers to a Document Type Definition (DTD).

Three.js is an open source JavaScript 3D library that enables you to make and display animated, interactive 3D computer graphics on any compatible web browser without having a dependency on proprietary plug-ins.

Key features of Three.js include

☛ Renderers
☛ Scenes
☛ Cameras
☛ Lights
☛ Animations
☛ Materials
☛ Shaders
☛ Objects
☛ Geometry
☛ Loaders
☛ Export/Import
☛ Debugging
☛ Support