Introduction to Javascript

Question 1

What is the full name of the book and in which year this book was released?

Answer 1

Javascript the definite guide. Seventh edition. Master the world`s most used language | 2020

Question 2

Define the most important techical aspects of Javascript.

Answer 2

JavaScript is a high-level, dynamic, interpreted language that is well suited for object-oriented and functional programming styles. It’s variables are untyped and it’s syntax is loosely based on Java but otherwise unrelated to the language. It derives its first class functions from Scheme language and its prototype based inheritance from Self language.

Question 3

Explain the concept of a ‘dynamic programming language’.

Answer 3

Dynamic programming language has the capability to run various programming concepts at runtime whilst other languages need to compile the code first. Here are the key characteristics of dynamic programming languages:
- dynamic variables
- runtime binding of variables.and methods aka the code can change itself during runtime
- reflection and introspection aka the code can change and generate new executable code
- advanced programming constructs like closures, first-class functions and prototype based inheritance

Question 4

Why JavaScript is called ECMAScript?

Answer 4

Because Sun Microsystems (now Oracle) registered JavaScript as a trademark back in the day. Netscape (now Mozilla) asked European Computer Manufacturers Association (ECMA) to standardise the language. As it was not possible to use a registered trademark as an official name the language was named as. ECMAScript in the documentation.

Question 5

The name of the first web browser and at what year it was released and by who?

Answer 5

WorldWideWeb which was later renamed to Nexus. Released in 1990 by CERN (European Centre for Nuclear Research) scientist Tim Berners-Lee

Question 6

In what year ES5 was released?

Answer 6

2010

Question 7

What version of JavaScript was compatible with all web browsers on 2020?

Answer 7

ECMAScript 5 aka. ES5

Question 8

In which year ES6 was released and what were it’s two major features?

Answer 8

2015
classes and modules
These major features uplifted JavaScript to become a general purpose language capable of building large-scale applications.

Question 9

Describe the naming logic of versioning after ES6.

Answer 9

EcmaScript + the release year eq. ES2016, ES2017 and so on.

Question 10

How to turn off the pre-ES5 mistakes?

Answer 10

By using ‘use strict’ directive

Question 11

What JS features turn on ‘use strict’ automatically in their contexts?

Answer 11

Using classes and modules.

Question 12

What JS core language does not include when compared to many other languages?

Answer 12

• input
• output
• networking
• storage
• graphics

Question 13

In which year Node become available；what it can do compared to the JS core language API; for.what is it commonly used?

Answer 13

• 2010
• read and write files, make and serve HTTP requests, send and receive data over network.
• For implementing web servers and for writing utility scripts as an alternative to Shell

Question 14

Describe JS’s most typical scenario for input and output?

Answer 14

User is giving input via mouse and keyboard and receiving output via CSS and HTML.

Question 15

JavaScript’s typing discipline in three words.

Answer 15

weak
duck
dynamic

Question 16

Define weak typing.

Answer 16

Weak typing means that the language has the ability to change the type of a variable to continue running the code. For example, it converts a number into a string in the following situation: ‘10 + “cat”. The benefits of such behaviour is that it helps the code to keep running despite the types mismatch and helps in writing less verbose code. The downside is that it can lead the code acting unexpectedly.