Node.js

Question 1

What is Node.js?

Answer 1

Node.js is a program that allows JavaScript to be run outside of a web browser. It’s also known as what’s called a runtime environment.

Question 2

What is a runtime environment?

Answer 2

A runtime environment is an environment in which a program or application can execute or be implemented.

Question 3

What is a REPL and what does the acronym stand for?

Answer 3

REPL stands for read-eval-print-loop. It’s a simple interactive programming environment that takes single user inputs, executes them, and results to the user.

For example, the console in our browsers is a REPL.

Question 4

What is blocking in JavaScript?

Answer 4

Blockingis when the execution of additional JavaScript in the Node.js process must wait until a non-JavaScript operation completes. This is what makes a language synchronous.

Question 5

What is non-blocking?

Answer 5

Non-blocking is the opposite of blocking where multiple operations can be performed at the same time. This is what makes a language asynchronous.

Question 6

What is the difference between a library and framework?

Answer 6

Libraries consist of functions that an application can call to perform a task while a framework defines how a developer designs an application.

Question 7

What is a computer process?

Answer 7

A computer process refers to a set of instructions currently being processed by the computer processor.

For example, if you look at your control panel or activity monitor, you’ll see that you have a lot of processes going on.

Question 8

What is the process object?

Answer 8

The process object is a global that provides info about, and control over, the current Node.js process. It’s always available to Node.js applications without using require( ).

Question 9

How do you access the process object in a Node.js program?

Answer 9

By calling the require function with ‘process’ as its argument.

Question 10

What does process.argv return?

Answer 10

Returns an array of arguments starting at the index 2. Index 1 is the file path of the executable that started the Node process while index 2 is the file path to the JavaScript file being executed.

Question 11

What is modular programming?

Answer 11

Separating behavior into multiple standalone functions.

Question 12

What is a module in Node.js?

Answer 12

A module is a single JS file.

Question 13

What does the require( ) function do?

Answer 13

The built-in function is the easiest way to include modules that exist in separate files. It reads a JavaScript file, executes the file, and then process to return the exports object.

Question 14

What does Node.js do specifically before a module’s mode is executed when loading modules?

Answer 14

Before a module’s code is executed, Node.js will wrap it with a function wrapper with the module code living in the code block of the function wrapper.

Question 15

What are the five parameters in a function wrapper before loading another module?

Answer 15

exports, require, module, __filename, __dirname

Question 16

When loading a module, are variables in the module code local or global?

Answer 16

Local because the module is wrapped in a function by Node.js

Question 17

What module does Node.js include for manipulating the file system?

Answer 17

fs module

Question 18

What is “utf8” and why do you need it in the readFile method?

Answer 18

Utf-8 is an encoding system that translates characters to matching binary strings. You need it in the method because the readFile method reads the file in binary so we need to encode it using utf-8.