Operadores (Parte1) - Curso JavaScript #07

Introduction and Advice

In the introduction, the speaker gives advice to take breaks between JavaScript classes and emphasizes the importance of practicing exercises.

Taking Breaks and Practicing

• It is recommended to take breaks between JavaScript classes.

• Resting and doing exercises can help give the brain a break.

• Practicing exercises on your own computer is essential for learning programming.

Questions to be Answered

The speaker introduces two questions that will be addressed in the class regarding saving values from prompts into variables and using numbers in calculations.

Saving Prompt Values and Using Numbers in Calculations

• How to save the value typed in a prompt inside a variable?

• Can numbers be used in calculations instead of names?

• Data manipulation is necessary for using values effectively.

• Can JavaScript convert names to uppercase with accents included using a single command?

• Is it possible to format monetary values with commas and decimal points using a single command?

Importance of Watching Previous Class

The speaker emphasizes the importance of watching the previous class if any of the questions mentioned earlier cannot be answered.

Importance of Watching Previous Class

• If unable to answer any of the previously mentioned questions, it indicates that the previous class was not watched.

• Click on the first playlist to access the JavaScript course.

Welcome Message

The speaker welcomes viewers to another lesson in their JavaScript course.

Welcome Message

• Viewers are welcomed to another lesson in their JavaScript course.

• Portuguese subtitles by Rayssa Victoria

• English translation and subtitles by William Vernaschi

Introduction to Class Number 7

The speaker introduces class number 7, which focuses on JavaScript operators.

Introduction to Class Number 7

• This is class number 7 of the JavaScript course.

• The class will cover JavaScript operators.

• Operators are divided into different families, including arithmetic, assignment, relational, logical, and ternary operators.

Operator Families in JavaScript

The speaker explains that there are several operator families in JavaScript but the focus of this course will be on arithmetic and assignment operators.

Operator Families in JavaScript

• There are various operator families in JavaScript.

• This course will focus on arithmetic and assignment operators.

• Other operator families include typeof, which was covered in a previous class.

Arithmetic Operators

The speaker introduces arithmetic operators as the first topic of discussion.

Arithmetic Operators

• Arithmetic operators are used for calculations in JavaScript.

• Programming does not require advanced math skills; basic everyday calculations such as percentages and averages are sufficient.

• The video will demonstrate how easy it is to perform arithmetic operations in JavaScript.

New Section

This section introduces the concept of operators and their operands in programming. The basic arithmetic operations of addition, subtraction, multiplication, division, whole division, remainder division, and exponentiation are explained.

Introduction to Operators

• Operators require two operands.

• The simplest operators are addition (+) and subtraction (-).

• Multiplication (*) is represented by an asterisk.

• Division (/) represents real division that includes decimal numbers.

• Whole division (%) calculates the remainder of a division.

• Exponentiation (**) raises a number to a power.

New Section

This section focuses on addition and subtraction as the two simplest arithmetic operations.

Addition and Subtraction

• Addition: 5 + 2 = 7

• Subtraction: 5 - 2 = 3

New Section

This section explains how to perform multiplication using the asterisk operator.

Multiplication

• Multiplication is represented by an asterisk (*).

• Example: 5 * 2 = 10

New Section

This section covers real division using the slash operator and introduces whole division using the percentage operator.

Division

• Real Division: Use the slash (/) operator. Example: 5 / 2 = 2.5

• Whole Division: Use the percentage (%) operator. Example: 5 % 2 = 1 (remainder of dividing 5 by 2)

New Section

This section further explains whole division and demonstrates how to calculate it step-by-step.

Whole Division Calculation

1. Divide: Start with dividend divided by divisor (e.g., 5 divided by 2).

2. Quotient: Write down the whole number quotient (e.g., 2).

3. Multiply: Multiply the divisor by the quotient (e.g., 2 * 2 = 4).

4. Subtract: Subtract the result from the dividend (e.g., 5 - 4 = 1).

5. Continue Dividing: If there is a remainder, place a comma next to the quotient and continue dividing.

6. Remainder: The final remainder is represented by the percentage operator (e.g., 5 % 2 = 1).

New Section

This section clarifies that the remainder obtained through whole division is represented by the percentage operator.

Understanding Whole Division

• The remainder obtained through whole division is represented by the percentage (%) operator.

• Example: The remainder of dividing 5 by 2 is represented as 5 % 2.

New Section

This section introduces exponentiation as a powerful arithmetic operation.

Exponentiation

• Exponentiation is performed using two asterisks (**).

• Example: 5 ** 2 = 25 (5 squared)

New Section

This section emphasizes caution when using operators due to operator precedence.

Operator Precedence

• Operator precedence determines which operation should be performed first in an expression.

• Example: In "5 + 3/2", division takes precedence over addition, resulting in a value of "6.5" instead of "4".

New Section

This section demonstrates examples of arithmetic operations using Node.js.

Examples with Node.js

• Use Node.js or any JavaScript environment to perform arithmetic operations.

• Examples:

• Addition: 5 + 2 = 7

• Whole Division: 9 % 2 = 1 (remainder of dividing 9 by 2)

• Real Division: 9 / 2 = 4.5

New Section

This section concludes the explanation of arithmetic operations and encourages note-taking for better understanding.

Conclusion and Note-Taking

• Recap the covered operators and their usage.

• Encourage viewers to take notes for future reference.

• Emphasize the importance of understanding operator precedence.

Timestamps are provided in the transcript to help locate specific parts of the video for further study.

Why did my math was wrong?

The instructor explains that programming languages only show errors for syntactic errors, not arithmetic mistakes. He demonstrates this by intentionally making a syntactic error and shows that it produces an error message. However, when he makes an arithmetic mistake, no error is shown because the expression is still syntactically correct.

Understanding Syntactic Errors

• Programming languages only display errors for syntactic errors.

• Making a syntactic error will result in an error message.

• Arithmetic mistakes may not produce error messages as long as the expression is still syntactically correct.

Not Receiving Error Messages

The instructor emphasizes that not receiving error messages does not necessarily mean the program is correct. It could indicate the absence of syntactic errors but still allow for incorrect calculations to be performed.

Importance of Error Messages

• Not receiving error messages does not guarantee correctness.

• Lack of error messages may indicate the absence of syntax errors but not necessarily accurate calculations.

• Programs should be carefully checked for both syntax and logical correctness.

Using Parentheses to Control Order of Operations

The instructor explains how to control the order of operations in mathematical expressions using parentheses in programming languages. He demonstrates an example where adding parentheses changes the order of precedence and results in different outcomes.

Controlling Order of Operations with Parentheses

• Parentheses can be used to change the order of precedence in mathematical expressions.

• Adding parentheses allows specific parts of an expression to be evaluated first before others.

• Examples are shown where adding or removing parentheses alters the outcome of calculations.

Arithmetic Operator Precedence Order

The instructor discusses the order of precedence for arithmetic operators in JavaScript and emphasizes its importance in correctly evaluating expressions. He explains that parentheses are evaluated first, followed by powers, multiplication/division, and addition/subtraction.

Order of Precedence for Arithmetic Operators

• Parentheses have the highest precedence and are evaluated first.

• Powers (exponentiation) have the next highest precedence.

• Multiplication, division, and remainder operations have the same level of precedence.

• Addition and subtraction operations have the lowest level of precedence.

• If multiple operators with the same precedence appear in an expression, they are evaluated from left to right.

Examples of Arithmetic Operations

The instructor demonstrates various arithmetic operations using JavaScript's arithmetic operators. He performs calculations such as addition, multiplication, and division without storing values in variables.

Performing Arithmetic Operations

• Examples of basic arithmetic operations are shown using JavaScript's arithmetic operators.

• Calculations include addition (+), multiplication (*), and division (/).

• Results are displayed on-screen without storing them in variables.

Storing Values in Variables

The instructor introduces variable assignment as a way to store values for later use. He explains how to declare variables using the "var" keyword and assigns values to them using the assignment operator (=).

Storing Values Using Variables

• Variables can be used to store values for later use.

• Variables are declared using the "var" keyword followed by a variable name.

• Values can be assigned to variables using the assignment operator (=).

Assigning Values to Variables

The instructor demonstrates assigning values to variables by performing calculations and storing results in different variables. He explains that when an expression is assigned to a variable, the value of the expression is stored in that variable.

Assigning Values to Variables

• Values can be assigned to variables using the assignment operator (=).

• Expressions can be assigned to variables, and their values will be stored in those variables.

• Examples are shown where calculations are performed and results are stored in different variables.

Order of Precedence with Multiple Operators

The instructor discusses how to determine the order of precedence when multiple operators with the same level of precedence appear in an expression. He encourages learners to refer back to the order of precedence chart and explains that division is evaluated before multiplication.

Determining Order of Precedence

• When multiple operators with the same level of precedence appear, refer back to the order of precedence chart.

• In JavaScript, division is evaluated before multiplication.

• Understanding order of precedence helps ensure correct evaluation of expressions.

Arithmetic Operations and Order of Precedence

In this section, the instructor explains arithmetic operations and the order of precedence in JavaScript.

Performing Arithmetic Operations

• The instructor demonstrates how to perform arithmetic operations using variables.

• Example: b = 3, e = 2. The remainder of 3 divided by 2 is 1. The first rectangle is assigned a value of 1. 4 divided by 2 gives a value of 2.

• The sum of the first rectangle (1) and the second rectangle (2) is calculated as 3.

Order of Precedence

• The instructor discusses the order in which calculations are performed, highlighting that addition was done last in the previous example.

• This concept is known as the order of precedence.

• It is important to write code and practice to understand this concept fully.

Example Code

• The instructor provides an example code snippet: var f = 3%2 + 4/2.

• He explains that JavaScript will perform the modulo operation first, then division, and finally addition.

• In this case, the value of f would be calculated as 3.

Undefined Values

• The instructor mentions that if a variable is not displayed on the screen, it may be considered undefined.

• To display a variable's value, use console.log() or other appropriate methods.

Self-Attributions

• Self-attributions are assignments to variables where they are attributed to themselves.

• Examples: n = n + 4, n = n -5, n = n *4, n = n /2, n = n **2, n = n %5.

• These self-attributions modify the value of the variable itself.

Simplified Assignment Operators

• Simplified assignment operators can be used to shorten self-attributions.

• Examples: n += 4, n -= 5, n *= 4, n /= 2, n **= 2, n %= 5.

• These operators are widely accepted in various programming languages.

Practical Example

• The instructor demonstrates a practical example using the variable num.

• Initial value of num is set to 8.

• Using the simplified assignment operator, the value of num is modified by adding or dividing it with other numbers.

Increment Operators

• Increment operators are introduced as another commonly used operator.

• Example: Setting variable x to 5 and incrementing it by one using the expression x = x + 1.

Assignment Operators and Increment Operators

In this section, the instructor continues discussing assignment operators and introduces increment operators.

Simplified Assignment Operators

• The instructor explains that self-attribution can be further simplified using shorthand notation.

• Examples: Instead of writing x = x + n, we can write it as x += n.

• This shorthand notation is applicable when the same variable receives the operation.

Increment Operators

• The instructor demonstrates how to use increment operators.

• Example: Setting variable x to 5 and incrementing it by one using the expression x++.

• This shorthand notation simplifies incrementing a variable by one.

Conclusion

The section covers arithmetic operations, order of precedence, self-attributions, simplified assignment operators, and increment operators. It provides examples and explanations for each concept.

New Section

This section discusses the simplification of mathematical operations in programming languages, specifically focusing on increment and decrement operators.

Simplifying Mathematical Operations

• The transcript explains that the expression x = x - 1 can be simplified as x -= 1.

• Similarly, the expression x = x + 1 can be simplified as x += 1.

• These simplifications are achieved using the increment (++) and decrement (--) operators.

• The order of these operators can affect the result. For example, n++ will show a different value compared to ++n.

• Pre-increment and post-increment, as well as pre-decrement and post-decrement, are briefly mentioned.

• While this may not make a significant difference in basic programming, it becomes more relevant in advanced programming.

New Section

In this section, the importance of foundational learning in JavaScript is emphasized before moving on to more advanced topics.

Importance of Foundational Learning

• The transcript encourages learners not to skip the initial learning phase and emphasizes its significance for future progress.

• Practical examples and interactive elements will be introduced later, but understanding fundamental concepts is crucial.

• Learners are encouraged to subscribe to the channel, enable notifications, interact with content, and access playlists for further learning.

New Section

This section provides guidance on navigating through JavaScript and HTML courses offered by the channel.

Navigating Through Courses

• Two courses are recommended: JavaScript course followed by HTML course.

• Both courses are closely linked and complement each other.

• It is suggested to complete the JavaScript course first before starting the HTML course.

• Completing both courses will provide a comprehensive understanding of web development.

New Section

The transcript concludes by mentioning the upcoming second part of the operator studies and expressing enthusiasm for learners' progress.

Conclusion and Next Steps

• Learners are reminded to attend the next class, which will cover the second part of operator studies.

• The transcript acknowledges that learners have already gained knowledge in mathematics and calculations through JavaScript learning.

• Encouragement is given to continue learning and not to skip foundational concepts.

Timestamps provided in the transcript have been used to structure the sections accordingly.