Web developmentLesson 1 of 2 in the course JavaScript and the browser

JavaScript Foundations: Language, Runtime, Asynchrony, and Security

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

JavaScript is one of the core technologies of the Web, alongside HTML and CSS. This lesson introduces the language, explains how it began, and follows the early efforts to standardize it.

JavaScript (JS) is a programming language widely used to make websites interactive. It is a high-level language with dynamic typing, first-class functions, and prototype-based object-oriented features. It supports imperative, functional, and event-driven programming styles.

All flashcards

ECMAScript
The standard specifying JavaScript's core language behavior; browser and runtime APIs are defined separately.
Prototype chain
The sequence of objects used when JavaScript looks up a property through prototypes.
Client-side validation
Browser-side checks that improve convenience but cannot replace security-critical server-side validation.
WebAssembly
A bytecode format that complements JavaScript, including for performance-sensitive web tasks.
Promise
An object representing the eventual fulfillment or rejection of an asynchronous operation.

Quiz questions

  1. What is the relationship between a JavaScript engine and its runtime?Answer: The engine executes code; the runtime exposes APIs for the surrounding environment.
  2. What does JavaScript's `class` syntax provide?Answer: Syntax for constructor and inheritance patterns built on prototypes.
  3. What does the same-origin policy generally restrict?Answer: A page's scripts reading protected data from a different origin.
  4. Which states can a JavaScript Promise occupy?Answer: Pending, fulfilled, or rejected.
  5. Which description of Node.js is accurate?Answer: A standalone runtime built around V8, with an event loop and I/O APIs.

Based on the Wikipedia article JavaScript, licensed CC BY-SA 4.0. Adapted into a summary, flashcards and quizzes.

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