JavaScript runtime overview - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a JavaScript runtime?

A JavaScript runtime is an environment where JavaScript code runs. It provides tools like memory management, event handling, and APIs to interact with the system or browser.

beginner

Name two popular JavaScript runtimes.

Two popular JavaScript runtimes are the browser (like Chrome's V8 engine) and Node.js, which runs JavaScript outside the browser.

intermediate

What role does the event loop play in the JavaScript runtime?

The event loop manages asynchronous tasks by checking the message queue and executing callbacks when the call stack is empty, allowing non-blocking code execution.

beginner

What is the call stack in a JavaScript runtime?

The call stack keeps track of function calls. It follows last-in, first-out order, running the top function and removing it when done before moving to the next.

intermediate

How does Node.js differ from browser JavaScript runtime?

Node.js provides extra APIs for file system, networking, and more, allowing JavaScript to run on servers, while browsers focus on web page interaction and DOM manipulation.

What does the JavaScript event loop do?

A Manages asynchronous tasks and executes callbacks

B Compiles JavaScript code to machine code

C Stores variables and functions

D Handles user interface rendering

The event loop manages asynchronous tasks by executing callbacks when the call stack is empty.

Which of these is NOT a JavaScript runtime?

A Chrome browser

B Python interpreter

C Node.js

D V8 engine

Python interpreter is not a JavaScript runtime; it runs Python code.

Where does JavaScript run in a browser?

A In the operating system kernel

B In the call stack only

C On the server only

D Inside the JavaScript runtime environment

JavaScript runs inside the browser's runtime environment, which includes the engine and APIs.

What is the call stack used for?

A Managing asynchronous events

B Storing global variables

C Tracking function calls in order

D Rendering HTML elements

The call stack tracks function calls in last-in, first-out order.

Which API is available in Node.js but NOT in browsers?

A File system access

B setTimeout

C DOM manipulation

D console.log

File system access is available in Node.js but not in browsers.

Explain the main components of a JavaScript runtime and how they work together.

Think about how JavaScript runs code and handles tasks that take time.

Describe the differences between running JavaScript in a browser and in Node.js.

Consider what each environment allows JavaScript to do.