What is JavaScript and how does it work? | Web Demystified, Episode 3 | Summary and Q&A

May 15, 2018
Mozilla Hacks
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What is JavaScript and how does it work? | Web Demystified, Episode 3


JavaScript is a highly asynchronous programming language that reacts to events, and it has different functionalities for browser and server-side programming.

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Questions & Answers

Q: What is the difference between JavaScript in the browser and JavaScript on the server?

JavaScript in the browser and on the server have different sets of utilities and functionalities. The browser-side JavaScript focuses on modifying HTML, making network requests, and rendering audio and graphics. On the other hand, server-side JavaScript allows for managing the computer directly, accessing files and folders, and handling network resources.

Q: How does JavaScript handle asynchronous tasks?

JavaScript has native asynchronous mechanisms that allow it to delegate tasks in the background. When an asynchronous task is completed, an event is emitted, which the JavaScript code can listen for and react to. This way, the browser doesn't freeze while waiting for time-consuming tasks like reading data from a database or making network requests.

Q: What are some key concepts behind JavaScript?

One of the key concepts behind JavaScript is its ability to react to events. JavaScript code can register event listeners that are triggered when certain events occur, such as the "load" event of the browser window. JavaScript also features object prototypes, first-class functions, internationalization, iteration, and closures.

Q: How does JavaScript interact with HTML?

JavaScript can be embedded in HTML using the <script> element. The JavaScript code can be written directly inside the element or in a separate file that is linked to the HTML document. It enables developers to manipulate HTML elements and interact with web standards APIs using JavaScript code.

Q: Why is JavaScript considered a powerful technology?

JavaScript is considered powerful because it has a wide range of functionalities and APIs available in the browser. It allows for dynamic web content, interactive user interfaces, and asynchronous processing. JavaScript's power comes with the responsibility of using it appropriately and efficiently to create robust web applications.

Q: Is JavaScript related to Java?

No, JavaScript is not related to Java despite the similar naming. JavaScript was named so for marketing purposes when Java was gaining popularity. JavaScript and Java are two completely different programming languages with distinct syntax, purposes, and functionalities.

Summary & Key Takeaways

  • JavaScript was standardized as ECMAScript in 1997, defining the core syntax and mechanisms of the language.

  • There are two flavors of JavaScript: browser-side and server-side, each with different functionalities.

  • JavaScript is highly asynchronous, allowing it to delegate tasks in the background and react to events.

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