Notice: This page requires JavaScript to function properly.
Please enable JavaScript in your browser settings or update your browser.Let 1/2 | Data Types and Variables
Introduction to JavaScript (staging)
course content

Course Content

Introduction to JavaScript (staging)

Introduction to JavaScript (staging)

1. Introduction
Writing our first codeOutput Using Variables 1/2Output Using Variables 2/2
2. JavaScript syntax
JavaScript SyntaxJavaScript VariablesJavaScript OperatorsIdentifiers in JavaScriptNaming IdentifiersReserved keywords in JavaScriptNaming Convention in JavaScript. Case StylesVariables Naming ConventionBoolean Naming ConventionConstant Naming ConventionFunction & Classes Naming ConventionMultiline StringsMultiline Strings. ConcatenatingCommenting in JavaScriptCommenting in JavaScript. Multi-line Comments
3. Data Types and Variables
What are Variables?What are Data-types?JavaScript and Type ConversionVar 1/3Var 2/3Var 3/3Let 1/2Let 2/2Constant 1/3Constant 2/3Constant 3/3Number 1/3Number 2/3Number 3/3Boolean 1/4Boolean 2/4Boolean 3/4Boolean 4/4Strings 1/5Strings 2/5Strings 3/5Strings 4/5Strings 5/5BigInt 1/3BigInt 2/3BigInt 3/3Symbols 1/3Symbols 2/3Symbols 3/3NullUndefinedNull vs Undefined

bookLet 1/2

In the very first chapter of the section we learn that there are three ways to declare a variable:

  • let
  • const
  • var

In the later versions of Javascript language known as ES6(ES2015), the let keyword was introduced. It works better than the var keyword. The variables written with the let keyword can also be overwritten.

let has Block Scope:

Variables declared with the let keyword has block scope and cannot be accessed outside that scope, for example.


              
1234

            
if (2 == 2){
    let  name = 'David'
}
console.log(name)
copy

As you can see we get an error that says that the name is not defined.
Note:
Don’t worry about the if and == for now they will be covered in the later chapters.

Task

In the following code, a variable named city with the assigned value of Berlin has been given to you. You are also given an if statement that checks whether 4 is greater than 2 or not (for now, don’t worry about the if). Your task is to declare a variable with the same name as above inside the if with the value of London. Display the variable outside the if.

Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
Everything was clear?

How can we improve it?

Thanks for your feedback!

Section 3. Chapter 7
toggle bottom row

bookLet 1/2

In the very first chapter of the section we learn that there are three ways to declare a variable:

  • let
  • const
  • var

In the later versions of Javascript language known as ES6(ES2015), the let keyword was introduced. It works better than the var keyword. The variables written with the let keyword can also be overwritten.

let has Block Scope:

Variables declared with the let keyword has block scope and cannot be accessed outside that scope, for example.


              
1234

            
if (2 == 2){
    let  name = 'David'
}
console.log(name)
copy

As you can see we get an error that says that the name is not defined.
Note:
Don’t worry about the if and == for now they will be covered in the later chapters.

Task

In the following code, a variable named city with the assigned value of Berlin has been given to you. You are also given an if statement that checks whether 4 is greater than 2 or not (for now, don’t worry about the if). Your task is to declare a variable with the same name as above inside the if with the value of London. Display the variable outside the if.

Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
Everything was clear?

How can we improve it?

Thanks for your feedback!

Section 3. Chapter 7
toggle bottom row

bookLet 1/2

In the very first chapter of the section we learn that there are three ways to declare a variable:

  • let
  • const
  • var

In the later versions of Javascript language known as ES6(ES2015), the let keyword was introduced. It works better than the var keyword. The variables written with the let keyword can also be overwritten.

let has Block Scope:

Variables declared with the let keyword has block scope and cannot be accessed outside that scope, for example.


              
1234

            
if (2 == 2){
    let  name = 'David'
}
console.log(name)
copy

As you can see we get an error that says that the name is not defined.
Note:
Don’t worry about the if and == for now they will be covered in the later chapters.

Task

In the following code, a variable named city with the assigned value of Berlin has been given to you. You are also given an if statement that checks whether 4 is greater than 2 or not (for now, don’t worry about the if). Your task is to declare a variable with the same name as above inside the if with the value of London. Display the variable outside the if.

Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
Everything was clear?

How can we improve it?

Thanks for your feedback!

In the very first chapter of the section we learn that there are three ways to declare a variable:

  • let
  • const
  • var

In the later versions of Javascript language known as ES6(ES2015), the let keyword was introduced. It works better than the var keyword. The variables written with the let keyword can also be overwritten.

let has Block Scope:

Variables declared with the let keyword has block scope and cannot be accessed outside that scope, for example.


              
1234

            
if (2 == 2){
    let  name = 'David'
}
console.log(name)
copy

As you can see we get an error that says that the name is not defined.
Note:
Don’t worry about the if and == for now they will be covered in the later chapters.

Task

In the following code, a variable named city with the assigned value of Berlin has been given to you. You are also given an if statement that checks whether 4 is greater than 2 or not (for now, don’t worry about the if). Your task is to declare a variable with the same name as above inside the if with the value of London. Display the variable outside the if.

Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
Section 3. Chapter 7
Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
some-alt