JavaScript If Else

What is Control Flow?

JavaScript Control Flow refers to the way in which the execution of code progresses through a script. Control flow determines the order in which statements are executed, depending on conditions, loops, or other constructs.

JavaScript If Else

The if...else statement in JavaScript controls code execution based on a specified condition. If the condition holds true, the code inside the if block runs. When the condition is false the else block (if defined) runs its statements.

Syntax:

  if (condition) {
    // Code to run if the condition is true
  } else {
      // Code to run if the condition is false
  }

Example:

Here’s a simple example:

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

Explanation:

• The variable age is set to 18.
• The if statement checks whether the condition age >= 18 is true.
  • If true, the message "You are eligible to vote." is displayed.
  • If false, the else block runs and displays "You are not eligible to vote."

Output:

You are eligible to vote.

Example with else if:

Multiple conditions can be handled using else if or nested if...else statements.

  let score = 85;
  if (score >= 90) {
      console.log("Grade: A");
  } else if (score >= 80) {
      console.log("Grade: B");
  } else if (score >= 70) {
      console.log("Grade: C");
  } else {
      console.log("Grade: F");
  }

Explanation:

• If the score is 90 or higher, the output will be "Grade: A".
• If the score is between 80 and 89, the output will be "Grade: B".
• If the score is between 70 and 79, the output will be "Grade: C".
• For any other score, the output will be "Grade: F".

This flexibility allows you to handle a variety of conditions in your program.