Conditionals In JavaScript

Java Code GeeksMay 31st, 2023Last Updated: May 31st, 2023

0 405 8 minutes read

Conditional statements, also known as conditionals, are an essential part of programming languages. They allow you to make decisions and execute different blocks of code based on certain conditions. Conditional statements enable your code to respond dynamically to different scenarios, making your programs more flexible and powerful.

In general, conditional statements evaluate a condition or a set of conditions and execute specific code blocks if the condition(s) is true or false.

How can you Implement Conditions

Conditions can be implemented using the following ways:

Conditions can be implemented in various ways in programming languages. Let’s explore some common methods along with code examples:

1. Comparison Operators: Comparison operators allow you to compare values and evaluate conditions based on the result. Here are some commonly used comparison operators:

Equal to (==): Checks if two values are equal.
Not equal to (!=): Checks if two values are not equal.
Strict equal to (===): Checks if two values are equal in value and type.
Strict not equal to (!==): Checks if two values are not equal in value or type.
Greater than (>): Checks if one value is greater than another.
Less than (<): Checks if one value is less than another.
Greater than or equal to (>=): Checks if one value is greater than or equal to another.
Less than or equal to (<=): Checks if one value is less than or equal to another.

Example:

let x = 5;
let y = 10;

if (x < y) {
  console.log("x is less than y");
} else if (x > y) {
  console.log("x is greater than y");
} else {
  console.log("x is equal to y");
}

2. Logical Operators: Logical operators allow you to combine conditions and create more complex expressions. The commonly used logical operators are:

Logical AND (&&): Returns true if both conditions are true.
Logical OR (||): Returns true if at least one condition is true.
Logical NOT (!): Inverts the result of a condition.

Example:

let age = 25;
let hasLicense = true;

if (age >= 18 && hasLicense) {
  console.log("You are eligible to drive");
} else {
  console.log("You are not eligible to drive");
}

3. Ternary Operator: The ternary operator allows you to write concise conditional expressions. It has the following syntax: condition ? expression1 : expression2. If the condition is true, expression1 is evaluated; otherwise, expression2 is evaluated.

Example:

let number = 7;
let result = number % 2 === 0 ? "Even" : "Odd";
console.log(result); // Output: Odd

4. Switch Statement: The switch statement provides an alternative to multiple if...else if statements when comparing a single value against multiple cases. It simplifies the code and improves readability.

Example:

let day = "Monday";

switch (day) {
  case "Monday":
    console.log("It's Monday");
    break;
  case "Tuesday":
    console.log("It's Tuesday");
    break;
  case "Wednesday":
    console.log("It's Wednesday");
    break;
  default:
    console.log("It's another day");
}

These are some common approaches to implementing conditions in programming. However, the specific method to use depends on the language you are working with and the requirements of your program.

Conditional Statements

In general, conditional statements evaluate a condition or a set of conditions and execute specific code blocks if the condition(s) is true or false. The most common types of conditional statements are:

if statement: The if statement is the simplest form of a conditional statement. It checks a condition and executes a block of code if the condition is true. Here’s the basic syntax:

if (condition) {
  // code to be executed if the condition is true
}

Here’s an example of using the if statement:

let age = 20;

if (age >= 18) {
  console.log("You are eligible to vote."); // This code block will be executed if the condition is true.
}

console.log("End of program.");

In this example, we have a variable age that represents a person’s age. The if statement checks if the age is greater than or equal to 18. If the condition evaluates to true, the code block inside the if statement will be executed, and the message “You are eligible to vote.” will be printed to the console. If the condition is false, the code block will be skipped, and the program will move on to the next line after the if statement.

Regardless of the condition’s outcome, the code outside the if statement will always be executed. In this case, “End of program.” will be printed to the console.

Note that the code inside the if statement is enclosed within curly braces {}. If the code block inside the if statement contains only one statement, the curly braces can be omitted. However, it is considered a good practice to always use curly braces to avoid any confusion or mistakes in the code.

The if statement is the most basic form of conditional statement and allows you to execute a block of code based on a single condition.

if…else statement: The if...else statement provides an alternative execution path. It checks a condition and executes one block of code if the condition is true, and a different block of code if the condition is false. Here’s the syntax:

if (condition) {
  // code to be executed if the condition is true
} else {
  // code to be executed if the condition is false
}

Here’s an example of using the if...else statement:

let time = 14;

if (time < 12) {
  console.log("Good morning!");
} else {
  console.log("Good afternoon!");
}

console.log("End of program.");

In this example, we have a variable time that represents the hour of the day. The if...else statement checks if the time is less than 12. If the condition evaluates to true, the code block inside the if statement will be executed, and the message “Good morning!” will be printed to the console. If the condition is false, the code block inside the else statement will be executed, and the message “Good afternoon!” will be printed to the console.

In this case, since the value of time is 14 (2 PM), the condition time < 12 is false. Hence, the code block inside the else statement will be executed, and “Good afternoon!” will be printed to the console.

After executing the appropriate code block, the program continues to the next line after the if...else statement, and “End of program.” will be printed to the console.

The if...else statement allows you to execute different code blocks based on a condition. If the condition is true, the code block inside the if statement is executed. If the condition is false, the code block inside the else statement is executed.

if…else if…else statement: The if...else if...else statement allows you to evaluate multiple conditions and execute the corresponding block of code based on the first true condition. Here’s the syntax:

if (condition1) {
  // code to be executed if condition1 is true
} else if (condition2) {
  // code to be executed if condition2 is true
} else {
  // code to be executed if all conditions are false
}

Here’s an example of using the if...else if...else statement:

let num = 0;

if (num > 0) {
  console.log("The number is positive.");
} else if (num < 0) {
  console.log("The number is negative.");
} else {
  console.log("The number is zero.");
}

console.log("End of program.");

In this example, we have a variable num that represents a number. The if...else if...else statement evaluates multiple conditions in sequence and executes the code block associated with the first condition that evaluates to true.

If num is greater than 0, the first condition num > 0 is true, and the code block inside the corresponding if statement will be executed, printing “The number is positive.” to the console.
If the first condition is false, the program moves to the next condition, num < 0. If num is less than 0, the second condition is true, and the code block inside the corresponding else if statement will be executed, printing “The number is negative.” to the console.
If both the first and second conditions are false, the program executes the code block inside the else statement, printing “The number is zero.” to the console.

After executing the appropriate code block, the program continues to the next line after the if...else if...else statement, and “End of program.” will be printed to the console.

The if...else if...else statement allows you to evaluate multiple conditions and perform different actions based on the first condition that evaluates to true.

switch statement: The switch statement provides a way to perform different actions based on multiple possible values of a single expression. It simplifies writing multiple if...else if statements. Here’s an example:

switch (expression) {
  case value1:
    // code to be executed if expression matches value1
    break;
  case value2:
    // code to be executed if expression matches value2
    break;
  default:
    // code to be executed if expression doesn't match any case
    break;
}

Here’s an example of using the switch statement:

let day = "Monday";

switch (day) {
  case "Monday":
    console.log("It's the first day of the week.");
    break;
  case "Tuesday":
    console.log("It's the second day of the week.");
    break;
  case "Wednesday":
    console.log("It's the third day of the week.");
    break;
  case "Thursday":
  case "Friday":
    console.log("It's a weekday.");
    break;
  case "Saturday":
  case "Sunday":
    console.log("It's a weekend day.");
    break;
  default:
    console.log("Invalid day.");
}

console.log("End of program.");

In this example, we have a variable day that represents a day of the week. The switch statement evaluates the value of day and executes the code block associated with the matching case.

If day is “Monday”, the code block inside the case "Monday": will be executed, printing “It’s the first day of the week.” to the console.
If day is “Tuesday”, the code block inside the case "Tuesday": will be executed, printing “It’s the second day of the week.” to the console.
Similarly, for “Wednesday”, “Thursday”, and “Friday”, the corresponding code blocks will be executed.
If day is “Saturday” or “Sunday”, the code block inside the case "Saturday": will be executed. Since there is no specific case for Sunday, the code block for case "Sunday": will also be executed. It will print “It’s a weekend day.” to the console.
If day doesn’t match any of the defined cases, the code block inside the default: will be executed, printing “Invalid day.” to the console.

After executing the appropriate code block, the program continues to the next line after the switch statement, and “End of program.” will be printed to the console.

The switch statement allows you to perform different actions based on multiple possible values of a single expression. It simplifies the code by avoiding multiple if...else if statements when comparing against multiple cases.

Conditional statements can be combined, nested, and used in various ways to handle complex decision-making scenarios. The conditions in conditionals are typically evaluated using comparison operators (e.g., ==, ===, !=, !==, <, >, <=, >=) or logical operators (e.g., && for logical AND, || for logical OR, ! for logical NOT).

By leveraging conditional statements, you can control the flow of your program, handle different inputs or scenarios, validate data, and create dynamic behaviors in your code. They are an essential tool for implementing branching logic and enabling your code to make informed decisions based on specific conditions.

Conclusion

In conclusion, conditional statements are fundamental constructs in programming languages that allow you to make decisions and execute different blocks of code based on specific conditions. They are essential for creating dynamic and flexible programs. Here’s a summary of the key points discussed:

Conditional statements, such as if, if...else, if...else if...else, and switch, enable your code to respond to different conditions and execute different code blocks accordingly.
Comparison operators (==, !=, ===, !==, <, >, <=, >=) are used to evaluate conditions based on the comparison of values.
Logical operators (&&, ||, !) are used to combine multiple conditions and create more complex expressions.
The ternary operator (condition ? expression1 : expression2) provides a concise way to write conditional expressions with two possible outcomes.
The switch statement allows you to compare a single value against multiple cases and execute different code blocks based on the matching case.
Conditional statements can be nested, combined, and used in various ways to handle complex decision-making scenarios in your programs.

By leveraging conditional statements effectively, you can control the flow of your code, handle different scenarios, validate data, and create dynamic behaviors. Understanding and applying conditional statements correctly is crucial for writing robust and reliable code.