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Introduction to TypeScript
course content

Course Content

Introduction to TypeScript

Introduction to TypeScript

1. TypeScript Fundamentals
What is TypeScript?SyntaxSimple variable declarationMathematics in TypeScriptTyped variable declarationCommentsCode Syntax Correction Challenge
2. Conditional Statements
Comparison Operatorsif statementIf-else statementDay of the Week Condition Execution ChallengeComplex ConditionsSwitchChallenge: Commission Calculator
3. Arrays
Declaration and Advantages of ArraysWorking with Array ElementsArray TypingChallenge: Modifying ArraysSpread Syntax
4. Loops
While-Loop`break` keywordDo-While LoopChallenge (snail game)`for` loop`for` loop with arrays Challenge (FizzBuzz)`forEach` method
5. Functions
Functions introductionParameters and Return StatementChallenge (lottery)Optional ParametersDefault ValuesChallenge (price calculator) Summary

book
If-else statement

Sometimes, one condition is not enough, and for that, in TypeScript (as in other programming languages), there is the if-else construct. For example, if you need to create a calculator, you, as a true programmer, will do it using the if-else construct, like this:


              
1234567891011121314

            
let a: number = 5;
let b: number = 10;
let operator: string = '*';
if (operator == '+') {
    console.log(a + b);
} else if (operator == '-') {
    console.log(a - b);
} else if (operator == '*') {
    console.log(a * b);
} else if (operator == '/') {
    console.log(a / b);
} else {
    console.log(`Error, there is no ${operator} operator!`)
}
copy

In this code, we have 3 variables: number a, number b, and the operation that will be performed between them. Using the if-else construct, we determine which operation will be applied to these two numbers. If we don't find a suitable operation, we will display a message indicating that such an operation is not available!

Now let's take a closer look at the syntax we're using:

javascript

Note that if one of the conditions is met, we exit the if-else statement, and the remaining blocks are ignored.

Unlike else if, the else block does not have a condition block. This is because else executes only if all previous conditions were false.

The if-else construct is often used for a variety of tasks, from checking if a number is positive to writing artificial intelligence.

You can also choose not to use else-if blocks and use only if and else, for example:


              
123456

            
let num: number = 15;
if (num >= 0) {
    console.log('The number is positive!');
} else {
    console.log('The number is negative');
}
copy

This way, we can experiment and use such a construct for various purposes!

1. What is the purpose of the if-else statement in TypeScript?

2. In an if-else statement, what is executed if the condition inside the if block is false?

question mark

What is the purpose of the if-else statement in TypeScript?

Select the correct answer

question mark

In an if-else statement, what is executed if the condition inside the if block is false?

Select the correct answer

Everything was clear?

How can we improve it?

Thanks for your feedback!

SectionΒ 2. ChapterΒ 3

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course content

Course Content

Introduction to TypeScript

Introduction to TypeScript

1. TypeScript Fundamentals
What is TypeScript?SyntaxSimple variable declarationMathematics in TypeScriptTyped variable declarationCommentsCode Syntax Correction Challenge
2. Conditional Statements
Comparison Operatorsif statementIf-else statementDay of the Week Condition Execution ChallengeComplex ConditionsSwitchChallenge: Commission Calculator
3. Arrays
Declaration and Advantages of ArraysWorking with Array ElementsArray TypingChallenge: Modifying ArraysSpread Syntax
4. Loops
While-Loop`break` keywordDo-While LoopChallenge (snail game)`for` loop`for` loop with arrays Challenge (FizzBuzz)`forEach` method
5. Functions
Functions introductionParameters and Return StatementChallenge (lottery)Optional ParametersDefault ValuesChallenge (price calculator) Summary

book
If-else statement

Sometimes, one condition is not enough, and for that, in TypeScript (as in other programming languages), there is the if-else construct. For example, if you need to create a calculator, you, as a true programmer, will do it using the if-else construct, like this:


              
1234567891011121314

            
let a: number = 5;
let b: number = 10;
let operator: string = '*';
if (operator == '+') {
    console.log(a + b);
} else if (operator == '-') {
    console.log(a - b);
} else if (operator == '*') {
    console.log(a * b);
} else if (operator == '/') {
    console.log(a / b);
} else {
    console.log(`Error, there is no ${operator} operator!`)
}
copy

In this code, we have 3 variables: number a, number b, and the operation that will be performed between them. Using the if-else construct, we determine which operation will be applied to these two numbers. If we don't find a suitable operation, we will display a message indicating that such an operation is not available!

Now let's take a closer look at the syntax we're using:

javascript

Note that if one of the conditions is met, we exit the if-else statement, and the remaining blocks are ignored.

Unlike else if, the else block does not have a condition block. This is because else executes only if all previous conditions were false.

The if-else construct is often used for a variety of tasks, from checking if a number is positive to writing artificial intelligence.

You can also choose not to use else-if blocks and use only if and else, for example:


              
123456

            
let num: number = 15;
if (num >= 0) {
    console.log('The number is positive!');
} else {
    console.log('The number is negative');
}
copy

This way, we can experiment and use such a construct for various purposes!

1. What is the purpose of the if-else statement in TypeScript?

2. In an if-else statement, what is executed if the condition inside the if block is false?

question mark

What is the purpose of the if-else statement in TypeScript?

Select the correct answer

question mark

In an if-else statement, what is executed if the condition inside the if block is false?

Select the correct answer

Everything was clear?

How can we improve it?

Thanks for your feedback!

SectionΒ 2. ChapterΒ 3
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