Variables play a crucial role in programming, allowing you to store and reuse values.

Note

A variable is like a container holding different data types, such as numbers, text, or more complex structures.

Before using variables, they must be defined. To define a variable, use the let keyword and choose a name for it:

let variableName;

Note

Variable names should follow the camelCase style. camelCase means that words are written together without spaces, and each word (except the first) is capitalized.

By default, a new variable contains the undefined value, indicating that no value has been assigned.

Note

The undefined value signifies that a value has not yet been assigned to the variable.

You can assign a value to a variable using the assignment operator (=):

let x;
x = 5;

Alternatively, you can assign a value when the variable is defined:

let x = 13;

Using Variables

Variables can be used to represent various values in your code and can be reused multiple times, reducing code repetition.


              1234
            
let word = "VariableText";  // The variable value is the `"VariableText"`

console.log("ValueText");  // Print the `"ValueText"`
console.log(word);  // Print the variable value

You can assign and reassign values to variables as needed:


              123456
            
let numb;
numb = 100;
console.log(numb);

numb = 100 + 20;
console.log(numb);

Variables are essential in programming because they allow you to reuse the same value many times. Consider a scenario where you've written 1000 lines of code using a specific value but made a typo that appears multiple times. In such a case, you'd need to correct every occurrence of that word in your code, which would be a significant waste of time.

Now, let's examine a similar example with fewer lines:


              1234
            
console.log("Hello Word!");
console.log("I love this Word!");
console.log("I need to live in this Word!");
console.log("This Word is the best!");

In this example, the author accidentally omitted the letter l in the word World. To fix this program, you only need to correct one occurrence of the typo.

Look at the following example:


              123456
            
let x = "Word";

console.log("Hello " + x + "!");
console.log("I love this " + x + "!");
console.log("I need to live in this " + x + "!");
console.log("This " + x + " is the best!");

You can fix it by changing one letter in the variable value from "Word" to "World". Please correct the provided example on your own.

Note

In the example above, we used string concatenation. We will delve into string concatenation in the next section.

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Seção 2. Capítulo 1

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Suggested prompts:

Can you explain more about string concatenation?

What are some common mistakes to avoid when naming variables?

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Variables play a crucial role in programming, allowing you to store and reuse values.

Note

A variable is like a container holding different data types, such as numbers, text, or more complex structures.

Before using variables, they must be defined. To define a variable, use the let keyword and choose a name for it:

let variableName;

Note

Variable names should follow the camelCase style. camelCase means that words are written together without spaces, and each word (except the first) is capitalized.

By default, a new variable contains the undefined value, indicating that no value has been assigned.

Note

The undefined value signifies that a value has not yet been assigned to the variable.

You can assign a value to a variable using the assignment operator (=):

let x;
x = 5;

Alternatively, you can assign a value when the variable is defined:

let x = 13;

Using Variables

Variables can be used to represent various values in your code and can be reused multiple times, reducing code repetition.


              1234
            
let word = "VariableText";  // The variable value is the `"VariableText"`

console.log("ValueText");  // Print the `"ValueText"`
console.log(word);  // Print the variable value

You can assign and reassign values to variables as needed:


              123456
            
let numb;
numb = 100;
console.log(numb);

numb = 100 + 20;
console.log(numb);

Now, let's examine a similar example with fewer lines:


              1234
            
console.log("Hello Word!");
console.log("I love this Word!");
console.log("I need to live in this Word!");
console.log("This Word is the best!");

In this example, the author accidentally omitted the letter l in the word World. To fix this program, you only need to correct one occurrence of the typo.

Look at the following example:


              123456
            
let x = "Word";

console.log("Hello " + x + "!");
console.log("I love this " + x + "!");
console.log("I need to live in this " + x + "!");
console.log("This " + x + " is the best!");

You can fix it by changing one letter in the variable value from "Word" to "World". Please correct the provided example on your own.

Note

In the example above, we used string concatenation. We will delve into string concatenation in the next section.

Tudo estava claro?

Obrigado pelo seu feedback!

Seção 2. Capítulo 1

Understanding Variables in JavaScript

Using Variables

Awesome!

Understanding Variables in JavaScript

Using Variables