Lessons

JavaScript Basics

Operators in JavaScript

Conditional Statements in JavaScript

JavaScript Strings

JavaScript Arrays

JavaScript Loop

JavaScript Functions

Conclusion

JavaScript break and continue Statements

JavaScript break and continue statements are used to control the behavior of loops. They allow you to exit a loop or skip specific iterations based on a condition, giving you more control over how the loop works.

The break Statement

The break statement is used to stop a loop entirely before it would naturally end. When a break statement is encountered, the program immediately exits the loop and continues executing the code after it.

Syntax

javascript
1
break;

Example: Exiting a Loop

In this example, the loop stops when the value of i equals 5:

javascript
1
2
3
4
5
6
7
8
9
10
let result = "";

for (let i = 0; i < 10; i++) {
  if (i === 5) {
    break; // Exit the loop when i equals 5
  }
  result += "Counting: " + i + "\n";
}

console.log(result);

Output:

javascript
1
2
3
4
5
Counting: 0
Counting: 1
Counting: 2
Counting: 3
Counting: 4

Why Use break?

  • To stop the loop early when a specific condition is met.
  • To save time and resources by avoiding unnecessary iterations.

The continue Statement

The continue statement skips the rest of the code in the current iteration and moves directly to the next iteration. Unlike break, it does not stop the loop entirely.

Syntax

javascript
1
continue;

Example: Skipping an Iteration

This example skips the iteration when i is an even number:

javascript
1
2
3
4
5
6
7
8
9
10
let output = "";

for (let i = 0; i < 10; i++) {
  if (i % 2 === 0) {
    continue; // Skip even numbers
  }
  output += "Odd number: " + i + "\n";
}

console.log(output);

Output:

javascript
1
2
3
4
5
Odd number: 1
Odd number: 3
Odd number: 5
Odd number: 7
Odd number: 9

Why Use continue?

  • To skip certain values or conditions without stopping the entire loop.
  • To avoid executing specific parts of a loop under certain conditions.

JavaScript Labels

JavaScript labels allow you to name a block of code and use it with break or continue. This is especially useful when dealing with nested loops, as it lets you break out of or continue specific loops.

Syntax

javascript
1
2
3
4
labelName: {
  // Code block
  break labelName;
}

Example: Breaking Out of a Labeled Block

Here’s how you can use a label to exit a code block:

javascript
1
2
3
4
5
6
7
8
outerBlock: {
  console.log("Start of block");
  if (true) {
    break outerBlock; // Exit the labeled block
  }
  console.log("This will not be logged");
}
console.log("End of block");

Output:

javascript
1
2
Start of block
End of block

Example: Using Labels with Nested Loops

When working with nested loops, you can use labels with continue to skip specific iterations of the outer loop:

javascript
1
2
3
4
5
6
7
8
outerLoop: for (let i = 1; i <= 3; i++) {
  for (let j = 1; j <= 3; j++) {
    if (i === j) {
      continue outerLoop; // Skip the outer loop iteration when i equals j
    }
    console.log(`i = ${i}, j = ${j}`);
  }
}

Output:

javascript
1
2
3
4
5
i = 1, j = 2
i = 1, j = 3
i = 2, j = 1
i = 3, j = 1
i = 3, j = 2

Key Points to Remember

  1. break: Stops the loop or code block entirely.
    • Use when you want to exit early from a loop or block.
  2. continue: Skips the current iteration and moves to the next one.
    • Use when you want to avoid specific iterations but continue the loop.
  3. Labels can be used to add flexibility when breaking out of or continuing nested loops or code blocks.

Frequently Asked Questions