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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

bookIdentifiers in JavaScript

What are JavaScript Identifiers

An identifier is simply a name. Identifiers are names given to entities like variables, arrays, functions, classes, etc. In programming, we often store some values in some variables for later use, and for this, we give some names to variables.

Rules for naming Identifier

  • Identifier names must start with a letter, an underscore _, or with a dollar sign $.

              
1234567891011

            
//valid identifier name
let greeting="hello world";
console.log(greeting);

//valid identifier name
let _greeting="Good night";
console.log(_greeting);

//valid identifier name
let $greeting="Good morning";
console.log($greeting);
copy

We got the output without any error which means that all our identifiers are according to JavaScript naming rules.

  • Identifier names cannot start with a number.

              
1

            
let 1number=10;
copy

If you run the code you can see the output says SyntaxError: Invalid or unexpected token which means that the token or the identifier we have used is invalid.

  • JavaScript is case-sensitive i.e. greeting is different from Greeting.

              
1234567

            
//different identifier name from below
let Greeting ="hello world";
console.log(Greeting);

//valid identifier name from above
let greeting="good morning";
console.log(greeting);
copy

Note: JavaScript reserves certain identifiers for use by the language itself. These reserved words cannot be used as regular identifiers. We'll consider it later.

Task

In the given javascript code rules for naming, identifiers are violated. Change the following names to make them correct. Then show the values on the console.

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 2. Chapter 4
toggle bottom row

bookIdentifiers in JavaScript

What are JavaScript Identifiers

An identifier is simply a name. Identifiers are names given to entities like variables, arrays, functions, classes, etc. In programming, we often store some values in some variables for later use, and for this, we give some names to variables.

Rules for naming Identifier

  • Identifier names must start with a letter, an underscore _, or with a dollar sign $.

              
1234567891011

            
//valid identifier name
let greeting="hello world";
console.log(greeting);

//valid identifier name
let _greeting="Good night";
console.log(_greeting);

//valid identifier name
let $greeting="Good morning";
console.log($greeting);
copy

We got the output without any error which means that all our identifiers are according to JavaScript naming rules.

  • Identifier names cannot start with a number.

              
1

            
let 1number=10;
copy

If you run the code you can see the output says SyntaxError: Invalid or unexpected token which means that the token or the identifier we have used is invalid.

  • JavaScript is case-sensitive i.e. greeting is different from Greeting.

              
1234567

            
//different identifier name from below
let Greeting ="hello world";
console.log(Greeting);

//valid identifier name from above
let greeting="good morning";
console.log(greeting);
copy

Note: JavaScript reserves certain identifiers for use by the language itself. These reserved words cannot be used as regular identifiers. We'll consider it later.

Task

In the given javascript code rules for naming, identifiers are violated. Change the following names to make them correct. Then show the values on the console.

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 2. Chapter 4
toggle bottom row

bookIdentifiers in JavaScript

What are JavaScript Identifiers

An identifier is simply a name. Identifiers are names given to entities like variables, arrays, functions, classes, etc. In programming, we often store some values in some variables for later use, and for this, we give some names to variables.

Rules for naming Identifier

  • Identifier names must start with a letter, an underscore _, or with a dollar sign $.

              
1234567891011

            
//valid identifier name
let greeting="hello world";
console.log(greeting);

//valid identifier name
let _greeting="Good night";
console.log(_greeting);

//valid identifier name
let $greeting="Good morning";
console.log($greeting);
copy

We got the output without any error which means that all our identifiers are according to JavaScript naming rules.

  • Identifier names cannot start with a number.

              
1

            
let 1number=10;
copy

If you run the code you can see the output says SyntaxError: Invalid or unexpected token which means that the token or the identifier we have used is invalid.

  • JavaScript is case-sensitive i.e. greeting is different from Greeting.

              
1234567

            
//different identifier name from below
let Greeting ="hello world";
console.log(Greeting);

//valid identifier name from above
let greeting="good morning";
console.log(greeting);
copy

Note: JavaScript reserves certain identifiers for use by the language itself. These reserved words cannot be used as regular identifiers. We'll consider it later.

Task

In the given javascript code rules for naming, identifiers are violated. Change the following names to make them correct. Then show the values on the console.

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!

What are JavaScript Identifiers

An identifier is simply a name. Identifiers are names given to entities like variables, arrays, functions, classes, etc. In programming, we often store some values in some variables for later use, and for this, we give some names to variables.

Rules for naming Identifier

  • Identifier names must start with a letter, an underscore _, or with a dollar sign $.

              
1234567891011

            
//valid identifier name
let greeting="hello world";
console.log(greeting);

//valid identifier name
let _greeting="Good night";
console.log(_greeting);

//valid identifier name
let $greeting="Good morning";
console.log($greeting);
copy

We got the output without any error which means that all our identifiers are according to JavaScript naming rules.

  • Identifier names cannot start with a number.

              
1

            
let 1number=10;
copy

If you run the code you can see the output says SyntaxError: Invalid or unexpected token which means that the token or the identifier we have used is invalid.

  • JavaScript is case-sensitive i.e. greeting is different from Greeting.

              
1234567

            
//different identifier name from below
let Greeting ="hello world";
console.log(Greeting);

//valid identifier name from above
let greeting="good morning";
console.log(greeting);
copy

Note: JavaScript reserves certain identifiers for use by the language itself. These reserved words cannot be used as regular identifiers. We'll consider it later.

Task

In the given javascript code rules for naming, identifiers are violated. Change the following names to make them correct. Then show the values on the console.

Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
Section 2. Chapter 4
Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
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