Operadores (Parte 2) - Curso JavaScript #08

Introduction and Questions

In this section, the instructor asks four questions to assess the viewer's knowledge of JavaScript concepts.

• What is the purpose of the percentage symbol operator in JavaScript?

• Solve the equation 6 + 4/2. Is the result 5 or 8?

• If a variable n has a value of 10 and we execute n += 5, what will be the new value of n?

• What happens when we use ++ or -- on the side of a variable?

Lesson Introduction

The instructor welcomes viewers to lesson eight of the JavaScript course and emphasizes the importance of watching part one before starting part two.

Recap and Reminder

The instructor reminds viewers to review previous lessons if they are unsure about any concepts covered so far.

Lesson Begins

The instructor officially starts lesson eight and introduces himself as Gustavo Guanabara, the teacher for this course.

Reviewing Operators from Part One

The instructor mentions that this class will continue discussing operators but will also refer back to operators covered in part one.

Relational Operators Introduction

The instructor explains that this class will cover relational operators, logical operators, and ternary operators in JavaScript.

Relational Operators Explanation

The instructor introduces relational operators (greater than, lesser than, greater than or equal to, lesser than or equal to, equal to, not equal to) and shares a trick for remembering which sign represents greater or lesser values.

Practical Examples with Relational Operators

The instructor demonstrates practical examples using relational operators and emphasizes that the result of any expression with a relational operator will always be a Boolean value (true or false).

Understanding Greater Than and Lesser Than Signs

The instructor provides a visual trick to differentiate between the greater than and lesser than signs.

Visual Trick for Greater Than and Lesser Than Signs

The instructor demonstrates a visual trick to remember which sign represents greater or lesser values.

Applying Relational Operators in JavaScript

The instructor applies relational operators to different expressions and explains how they evaluate to true or false.

Equality Operator in JavaScript

The instructor clarifies that the equality operator in JavaScript is represented by two equal signs (==) rather than one, which is an assignment operator.

Examples with Equality Operator

The instructor provides examples using the equality operator (==) to compare values in JavaScript.

Not Equal Operator Explanation

The instructor explains the meaning of the "!=" operator, which checks if two values are not equal.

Examples with Not Equal Operator

The instructor provides examples using the "!=" operator to compare values in JavaScript.

Due to time constraints, only key sections have been summarized.

Opening Node.js on Windows

The instructor demonstrates how to open Node.js on a Windows system and explains that it can also be opened through Visual Studio. They mention the ability to perform various operations using variables and relational operators.

Opening Node.js

• Open Node.js on Windows by typing "Node" in the command prompt.

• Alternatively, it can be opened through Visual Studio.

• Once inside Node.js, various operations can be performed using variables and relational operators.

Comparing Numbers and Variables

The instructor demonstrates how to compare numbers using relational operators and showcases examples with variables.

Comparing Numbers

• Compare if 5 is greater than 2 (true).

• Compare if 8 is less than 4 (false).

• Comparison can also be done with variables.

• Example: Variable "a" assigned as 8, variable "b" assigned as 15.

• Test if "a" is greater than "b" (false).

Combining Expressions with Relational Operators

The instructor shows how to combine expressions containing arithmetic and relational operators.

Combining Expressions

• Example expression: a <= b - 10.

• Evaluate the expression step by step:

• Calculate b - 10 which equals 5.

• Is a less than or equal to b - 10? (false)

More Examples of Comparison Operations

The instructor provides additional examples of comparison operations using different scenarios.

Additional Examples

• Perform comparisons with clear variable names:

• Is the price greater than or equal to $200.50?

• Is the age less than 18?

• Is the course equal to "JavaScript"?

• Are n1 and n2 not equal?

Understanding Comparison Operations

The instructor explains the concept of comparison operations and introduces identity operators.

Understanding Comparisons

• Clarification on specific comparisons:

• Price comparison checks if it is greater than or equal to $200.50.

• Age comparison checks if a person is under 18 years old.

• Course comparison checks if it is equal to "JavaScript".

• n1 and n2 are compared for inequality.

Identity Operators

The instructor introduces identity operators, also known as strict equality operators, and provides examples.

Identity Operators

• Introduction to identity operators:

• Example: 5 == 5 (true).

• Comparison between different types:

• Example: 5 == '5' (true).

• Explanation that JavaScript compares values regardless of type.

• Introduction to strict equality operator (===) which considers both value and type.

Strict Equality Operator

The instructor further explains the strict equality operator and demonstrates its usage.

Strict Equality Operator

• Explanation of strict equality operator (===) usage:

• Example: 5 === 5 (false).

• Demonstrates that two fives with different types are not identical.

• Mention that three equals signs are used for strict equality comparisons.

Practical Examples in Node.js

The instructor encourages practical application by demonstrating examples in Node.js.

Practical Examples

• Encouragement to practice and experiment in Node.js.

• Demonstrates examples using variables and comparison operators.

• Suggests referring to the provided examples for further practice.

Conclusion of Relational Operators

The instructor concludes the topic of relational operators and mentions upcoming lessons on logical operators.

Conclusion

• Recap of covered content on relational operators.

• Mention of upcoming lessons on logical operators.

Desenvolvimento Web - Aula 5 Introdução ao Desenvolvimento Web

Nesta aula, o professor introduz os conceitos básicos do desenvolvimento web e explica como criar um site integrado com JavaScript.

Introdução ao Desenvolvimento Web

• O professor explica que é possível solicitar uma caneta específica, por exemplo, "Eu quero uma caneta que não seja azul" .

• Ele destaca a importância de praticar e treinar para realmente aprender .

• Na próxima aula, será abordado o conceito de DOM e como integrar JavaScript com HTML e CSS .

• Serão fornecidas orientações sobre a instalação de programas extras no Visual Studio Code e Google Chrome para iniciar o desenvolvimento web .

• É enfatizado que é necessário praticar todos os conhecimentos adquiridos nas aulas anteriores .

Keep in mind that the timestamps provided are approximate and may not be exact.