Condições (Parte 2) - Curso JavaScript #12

Name: Condições (Parte 2) - Curso JavaScript #12
Uploaded: 2019-05-27T16:00:00.000Z
Duration: 58 min 20 s

Introduction and Questions

In this section, the instructor introduces the 12th lesson of the JavaScript course and poses some questions to assess the viewers' knowledge.

The instructor asks if the viewers know how to use the Node Exec extension in Visual Studio Code.

It is emphasized that understanding how to create conditions in JavaScript is important.

The viewers are asked if they know about JavaScript relational operators and how to differentiate between simple and compound conditions in code.

Lesson Introduction

The instructor welcomes the viewers to the 12th lesson of the JavaScript Video Course and mentions that this part focuses on conditions in JavaScript.

Importance of Practice

The instructor emphasizes the importance of practicing exercises from previous lessons for better understanding.

Viewers are encouraged to practice and apply what they have learned.

Practicing is compared to filling a bag with knowledge.

Simple Conditions vs Compound Conditions

This section explains the difference between simple conditions (if statements without an else clause) and compound conditions (if statements with multiple blocks).

Simple conditions involve executing a block of code if a certain condition is satisfied.

Compound conditions allow for multiple blocks of code based on different conditions.

It is stressed that watching part 1 (lesson 11) before proceeding with part 2 (lesson 12) is essential for a complete understanding.

Handling Multiple Possibilities

This section discusses situations where there are multiple possibilities for handling data.

Simple and compound conditions may not be sufficient when there are several ways to treat given data.

Aligned conditions, where multiple conditions are nested within each other, provide more flexibility.

The instructor demonstrates how aligned conditions can expand the possibilities for executing different blocks of code.

Creating Aligned Conditions

This section explains how to create aligned conditions in JavaScript.

Aligned conditions involve nesting multiple conditions within each other.

By aligning conditions, it is possible to have more than two possibilities for executing different blocks of code.

The instructor highlights that there is no strict rule for alignment and it depends on the specific situation.

JavaScript Structure for Aligned Conditions

This section mentions a JavaScript structure specifically designed for aligned conditions.

JavaScript provides a structure or command that facilitates creating aligned conditions.

The instructor encourages viewers to explore and utilize this structure when working with aligned conditions.

Timestamps may not be available for every bullet point as per the given transcript.

Condição Alinhada em JavaScript

Neste trecho, o instrutor introduz a estrutura de condição alinhada em JavaScript, explicando como escrever uma condição dentro de outra. Ele destaca a importância do recuo (indentação) correto e mostra como executar diferentes blocos de código com base nas condições.

Estrutura da Condição Alinhada

A estrutura da condição alinhada consiste em escrever uma condição dentro de outra.

O recuo (indentação) adequado é fundamental para indicar que um bloco de código está dentro do outro.

Se a primeira condição for verdadeira, o bloco 1 será executado. Caso contrário, o programa verificará a segunda condição.

Se a segunda condição for verdadeira, o bloco 2 será executado. Caso contrário, o programa passará para outra condição ou bloco.

Aninhamento Adicional e Raciocínio Lógico

É possível adicionar mais níveis de aninhamento ao incluir outras condições dentro dos blocos existentes.

Para executar um bloco interno, as condições externas devem ser falsas.

O raciocínio lógico é essencial para determinar quais blocos serão executados com base nas combinações das diferentes condições.

Exemplo Prático em JavaScript

Nesta parte do vídeo, o instrutor demonstra um exemplo prático usando Visual Studio Code e Node.js para executar códigos JavaScript. Ele cria uma variável "idade" e utiliza uma estrutura condicional para determinar se a pessoa é menor ou maior de idade.

Exemplo Prático

Utilizando o Visual Studio Code, crie uma nova pasta e um novo arquivo JavaScript.

Declare uma variável "idade" e atribua um valor numérico a ela.

Utilize a estrutura condicional "if" para verificar se a idade é menor que 18.

Se a condição for verdadeira, exiba no console a mensagem "menor de idade".

Caso contrário, exiba a mensagem "maior de idade".

Personalizando as Mensagens

Nesta parte do vídeo, o instrutor mostra como personalizar as mensagens exibidas com base nas condições. Ele substitui as mensagens padrão de "maior de idade" e "menor de idade" por "vota" e "não vota", respectivamente.

Personalização das Mensagens

Em vez de utilizar as mensagens padrão de "maior de idade" e "menor de idade", é possível personalizar as mensagens conforme necessário.

No exemplo prático anterior, substitua as mensagens por "vota" e "não vota".

Execute o código novamente para ver as novas mensagens sendo exibidas no console.

The transcript provided is in Portuguese.

Nested If Statements

In this section, the speaker discusses nested if statements in JavaScript. They explain how to write code with multiple conditions and demonstrate the use of indentation to represent nested structures.

Understanding Nested If Statements

Nested if statements involve having one if statement inside another.

Indentation is used to visually represent the nesting structure.

The inner if statement is only executed if the condition of the outer if statement is true.

Multiple levels of nesting are possible, but it's important to keep the code readable.

Execution Flow in Nested If Statements

If the condition of the outer if statement is true, it executes its corresponding block of code.

If the condition of the outer if statement is false, it moves on to check the condition of the inner if statement.

If the condition of the inner if statement is true, it executes its corresponding block of code.

It's essential to understand that for a nested block to execute, all preceding conditions must be false.

Adding More Levels of Nesting

It's possible to add more levels of nesting by placing another if statement inside an existing one.

Each level adds complexity and requires careful consideration for readability and logic flow.

Practical Example in JavaScript

The speaker demonstrates a practical example using JavaScript:

let age = 22;

if (age < 18)

console.log("Minor");

else

console.log("Adult");

In this example, "Minor" or "Adult" will be printed based on whether age is below or equal to 18.

Understanding Error Messages

In this section, the speaker discusses the absence of error messages and their significance within a program.

Importance of Error Messages

Lack of error messages can indicate that there are no errors in the code.

The absence of errors allows for smooth execution within the program.

Obtaining Current System Time

This section focuses on retrieving the current system time within a script and its relevance based on whether it is running on a client or server.

Getting Current System Time

The current system time depends on whether the script is running on the client or server.

If running on the client, it reflects the client's time. If running on the server using Node.js, it reflects the server's time.

Multiple Conditional Statements for Fixed Values

The speaker introduces multiple conditional statements for fixed values and explains their usefulness in programming.

Multiple Conditional Statements

Multiple conditional statements are useful when working with fixed values.

They are not suitable for handling value ranges like "good morning," "good afternoon," and "good evening."

Working with Multiple Conditions

This section explores multiple conditions in programming and how they allow testing various values before returning to normal program flow.

Structure of Multiple Conditions

Multiple conditions involve testing different values within an expression.

After evaluating each condition, control returns to the regular flow of the program.

Specific Use Cases for Multiple Conditions

The speaker highlights that multiple conditions are applicable only in specific situations and recommends taking notes to understand their structure better.

Specific Use Cases

Multiple conditions are not universally applicable like the if-else if structure.

They are useful for handling specific, isolated situations.

Taking notes and drawing diagrams can aid in understanding and retaining the structure.

Introduction to Switch Statements

This section introduces switch statements as an alternative conditional structure and explains their syntax.

Switch Statements

Switch statements are expressed using the "switch" keyword.

Each case represents a different value to be tested against.

The "default" clause functions similarly to an "else" statement, executing when none of the previous cases match.

Break Statement in Switch Statements

The speaker emphasizes the importance of including a break statement within each case block in switch statements.

Break Statement

A break statement is required within each case block of a switch statement.

It ensures that execution exits the switch block after a matching case is found.

Timestamps have been associated with relevant bullet points.

Understanding the usage of switch statements in JavaScript

In this section, the speaker explains the importance of using break statements in switch statements and how they affect the flow of execution.

Importance of break statements in switch statements

The speaker emphasizes that it is crucial to include break statements in each case of a switch statement.

Without break statements, the code will continue executing all subsequent cases until it finds a break statement.

The flow of execution automatically follows the yellow arrow to the next command after encountering a break statement.

Each break statement is mandatory and serves as an exit point for the switch block.

If a break statement is missing, it can lead to problems as all subsequent commands will be executed until a break statement is encountered.

It is essential to remember and take note of this requirement to avoid issues when working with switch statements.

Practice and practical examples

The speaker encourages practicing and suggests returning to Visual Studio Code for further examples.

A new file named "ex013.js" is created for demonstration purposes.

The speaker introduces working with dates using JavaScript's new Date() function.

The day of the week can be obtained using getDay(), where Sunday corresponds to 0, Monday to 1, Tuesday to 2, and so on.

The speaker clarifies that Sunday is considered day 0, Monday as day 1, and so on, according to JavaScript's getDay() function.

The speaker mentions that using a switch statement can simplify the code for handling different days of the week.

Each case represents a specific day, and the corresponding action is executed.

In case none of the specified cases match the day of the week, a default case can be used to handle invalid inputs.

Timestamps are approximate and may vary slightly.

Handling Errors in Code

In this section, the speaker discusses the absence of commands below and explains that they will be addressing error handling later.

Importance of Error Handling

The absence of commands below is a case related to potential problems.

Error handling will be addressed in future discussions.

Timestamps are provided for each bullet point to help locate the corresponding part of the video.