JavaScript Fundamentals - Part One

Question 1

What is a variable?

Answer 1

A variable is a container for a value, like a number we might use in a sum, or a string that we might use as part of a sequence.

Question 2

How to declare a variable?

Answer 2

let myName;

Question 3

How to initialize a variable?

Answer 3

let myName = “Chris”;

Question 4

How to redeclare a variable?

Answer 4

myName = “Bob”;

Question 5

What are the 7 primitive data types of JavaScript?

Answer 5

Number, String, Boolean, Undefined, Null, Symbol, BigInt

Question 6

What is the difference between let, const, and var?

Answer 6

We use var if we want function-scoped variables that can be hoisted. let if we want block-scoped variables that can be reassigned. And const if we want block-scoped variables that are constant and cannot be reassigned.

Question 7

What are the JavaScript Operators?

Answer 7

Assignment Operators, Arithmetic Operators, Comparison Operators, Logical Operators, Bitwise Operators, String Operators, other JavaScript Operators.

Question 8

What are the Assignment Operators?

Answer 8

=, +=, -=, *=, /=, %=, **=.

Question 9

What are the Arithmetic Operators?

Answer 9

+, -, *, /, %, ++, –, **.

Question 10

What are the Comparison Operators?

Answer 10

==, !=, ===, !==, >, >=, <, <=.

Question 11

What are the Logical Operators?

Answer 11

&&, ||, !.

Question 12

What are the Bitwise Operators?

Answer 12

&, |, ^, ~, «,&raquo_space;,&raquo_space;>.

Question 13

What are the String Operators?

Answer 13

Used to concatenate (join) two or more strings.

Question 14

What are others JavaScript Operators?

Answer 14

(,), ?:, delete, typeof, void, in, instanceof

Question 15

What is Operator Precedence in JavaScript?

Answer 15

Operator precedence in JavaScript determines the priority of operators in an operation. It determines which operators have higher precedence than others, and thus tells us the order to perform a given mathematical expression. Operators with higher precedence will become the operands of operators with lower precedence.

Question 16

What are Template Literals?

Answer 16

Template literals are literals delimited with backtick (``) characters, allowing for multi-line strings, string interpolation with embedded expressions, and special constructs called tagged templates.

Question 17

What is the use of the if/else statement?

Answer 17

The if…else statement executes a statement if a specified condition is truthy. If the condition is falsy, another statement in the optional else clause will be executed.

Question 18

What is the difference between type coersion and type conversion in JavaScript?

Answer 18

Type coercion happens implicitly during operations or comparisons, where JavaScript automatically converts values to make them compatible. Type conversion, on the other hand, involves explicit conversion of values using functions or operators provided by JavaScript.

Question 19

What are truthy and falsy in JavaScript?

Answer 19

When non-boolean values are used in a boolean context, such as the condition of an if statement, they will be coerced into either true or false. Values that are coerced into true are called truthy and values that are coerced into false are called falsy.

Question 20

What is Strict Equality in JavaScript? How does it differ from the loose equality operator?

Answer 20

The strict equality (===) operator checks whether its two operands are equal, returning a Boolean result. Unlike the equality operator, the strict equality operator always considers operands of different types to be different.

Question 21

What are Logical Operators in JavaScript?

Answer 21

There are three logical operators in JavaScript: && (AND), || (OR), and !(NOT).

Question 22

Explain the OR(||) Operator.

Answer 22

It evaluates the operands from left to right and returns true whenever it encounters the first truthy value otherwise false.

Question 23

Explain the AND(&&) Operator.

Answer 23

Its operands will be true if and only if all the operands are true.

Question 24

Explain the NOT(!) Operator.

Answer 24

The logical NOT operator flips the value of a boolean. If the value is true, the NOT operator returns false. If the value is false, the NOT operator returns true.

Question 25

What is the Switch Statement in JavaScript?

Answer 25

The switch statement executes a block of code depending on different cases. The switch statement is a part of JavaScript’s Conditional Statements, which are used to perform different actions based on different conditions. Use switch to select one of many blocks of code to be executed.

Question 26

What is the difference between a Statement and an Expression in JavaScript?

Answer 26

Expression is a bit of a JavaScript code that produces a value. For example: 1 -> produces 1, “hello” -> produces “hello”. A JavaScript program, for instance, is a sequence of statements. Each statement is an instruction for the computer to do something. For example: let hi = 5, throw new Error(“Something exploded!”).

Question 27

What is a Ternary Operator?

Answer 27

A ternary operator can be used to replace an if…else statement in certain situations. A ternary operator evaluates a condition and executes a block of code based on the condition.