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JavaScript Conditional Statements: Using if ifelse and ifelseif

Introduction to JavaScript if else if statement

JavaScript is a popular programming language that is used to create dynamic websites and web applications. As a programmer, one of the most important concepts to understand is the use of conditional statements.

In JavaScript, the most commonly used conditional statements are the if and if…else statements. It helps you control the flow of your program and make decisions based on certain conditions.

However, there are cases where you may need to test multiple conditions, and that’s where if…else…if statements come into play. In this article, we’ll explain how to use if and if…else statements and how to write if…else…if statements in JavaScript.

Explanation of if and if…else statements

The if statement is used to test whether a condition is true or false. If the condition is true, a block of code is executed.

If the condition is false, the block of code is skipped. Here’s an example of how to use the if statement in JavaScript:

if (1 + 1 === 2) {

console.log(“The condition is true”);

}

In this example, if the condition (1 + 1 === 2) is true, the console.log statement will be executed.

The if…else statement is used when you want to execute a different block of code when the condition is false. Here’s an example:

if (1 + 1 === 3) {

console.log(“The condition is true”);

} else {

console.log(“The condition is false”);

}

In this example, since the condition is false, the second block of code will be executed and the message “The condition is false” will be logged to the console.to if…else…if statement

Sometimes you need to check more than one condition in your code.

That’s where the if…else…if statement comes in. The if…else…if statement allows you to test multiple conditions, and each condition is checked one by one until a true condition is found.

When a true condition is found, the associated block of code is executed, and the other blocks are skipped. Here’s an example:

if (num > 0) {

console.log(“Positive number”);

} else if (num === 0) {

console.log(“Zero”);

} else {

console.log(“Negative number”);

}

In this example, three conditions are checked sequentially.

If the number is greater than 0, the first block of code is executed. If the number is equal to 0, the second block of code is executed.

If the number is less than 0, the third block of code is executed.

JavaScript if else if examples

Now that we’ve covered the basics of if and if…else statements and if…else…if statements, let’s look at some examples of how they can be used in JavaScript. Example 1: Month name conversion

Suppose you have an integer that represents a month (1 for January, 2 for February, etc.), and you want to convert it to the corresponding month name.

Here’s a code snippet that does that using if…else…if statements:

const month = 4;

let monthName;

if (month === 1) {

monthName = “January”;

} else if (month === 2) {

monthName = “February”;

} else if (month === 3) {

monthName = “March”;

} else if (month === 4) {

monthName = “April”;

} else if (month === 5) {

monthName = “May”;

} else if (month === 6) {

monthName = “June”;

} else if (month === 7) {

monthName = “July”;

} else if (month === 8) {

monthName = “August”;

} else if (month === 9) {

monthName = “September”;

} else if (month === 10) {

monthName = “October”;

} else if (month === 11) {

monthName = “November”;

} else if (month === 12) {

monthName = “December”;

} else {

monthName = “Invalid month”;

}

console.log(monthName);

In this example, the code checks each possible value of the month variable using if…else…if statements, and sets the monthName variable to the corresponding month name string. If the month variable is not between 1 and 12, the code sets the monthName variable to “Invalid month”.

Example 2: Body mass index calculation

Another example where if…else statements are useful is in calculating the Body Mass Index (BMI) and determining the weight status of a person. Here’s an example:

const weight = 70; // in kilograms

const height = 1.75; // in meters

const bmi = weight / (height * height);

if (bmi < 18.5) {

console.log(“Underweight”);

} else if (bmi < 25) {

console.log(“Normal weight”);

} else if (bmi < 30) {

console.log(“Overweight”);

} else {

console.log(“Obese”);

}

In this example, the code calculates the BMI using the weight and height variables, and then determines the weight status of the person using if…else statements based on the value of the BMI variable.

If the BMI is less than 18.5, the code logs “Underweight”. If the BMI is between 18.5 and 24.9, the code logs “Normal weight”.

If the BMI is between 25 and 29.9, the code logs “Overweight”. If the BMI is 30 or greater, the code logs “Obese”.

Conclusion

Conditional statements are an important concept in programming as they allow you to control the flow of your code and make decisions based on different conditions. The if statement and if…else statement are the most commonly used conditional statements in JavaScript.

If…else…if statements are used when you need to check multiple conditions. Hopefully, this article has given you a good introduction to these concepts and some practical examples of how they can be used in real-world situations.

In this article, we have covered the basics of if and if…else statements and the if…else…if statement in JavaScript. We have also provided examples of how these statements can be used in real-world situations, such as converting a month’s integer value to a corresponding month name and determining the weight status of a person based on their BMI.

To summarize, the if statement is used to test whether a condition is true or false, and if it’s true, a block of code is executed. The if…else statement is used when you want to execute a different block of code when the condition is false.

The if…else…if statement allows you to check multiple conditions, and each condition is checked one by one until a true condition is found. We have looked at two examples that demonstrate the use of these statements.

In the first example, we used if…else…if statements to convert an integer representing a month to the corresponding month name. In the second example, we used if…else statements to determine the weight status of a person based on their BMI.

When writing JavaScript code, it is essential to be accurate and clear while using these statements. Accuracy helps to ensure that your code works as intended, while clarity makes it easier for other programmers to understand your code.

It is also essential to break down your code into smaller subtopics and use primary keywords to help your readers better understand your code’s functionalities. Using these subtopics and primary keywords in your code helps to improve the organization and readability of your code.

In conclusion, understanding the basics of if and if…else statements and the if…else…if statement in JavaScript is crucial to developing effective code. By using these conditional statements, you can create more dynamic and flexible programs that can handle multiple situations.

Remember to be accurate and clear when using these statements and to use subtopics and primary keywords to organize your code effectively. In this article, we have discussed the importance of conditional statements in JavaScript coding, focusing on the if and if…else statements as well as the if…else…if statement.

We have explored how to use these statements and provided examples to demonstrate their practical applications. Clear and precise coding is important when using these statements, and integrating primary keywords and subtopics can significantly improve code organization and readability.

Overall, understanding conditional statements is crucial in creating dynamic and flexible programs capable of handling various conditions. By following the guidelines outlined in this article, programmers can write effective, accurate, and easily understandable code.

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