Understanding the basics

JavaScript provides several ways to iterate over data structures. In this blog post, we will explore different types of loops and when to use each one.

for Loop

The for loop is the most commonly used loop in JavaScript. It has three parts: initialization, condition, and increment/decrement.

for (let i = 0; i < 5; i++) {
  console.log(i); // 0, 1, 2, 3, 4
}

In the above example, the loop runs five times, logging the values from 0 to 4.

while Loop

The while loop continues to execute as long as the specified condition is true.

let i = 0;
while (i < 5) {
  console.log(i); // 0, 1, 2, 3, 4
  i++;
}

In the above example, the loop runs while i is less than 5.

do...while Loop

The do...while loop is similar to the while loop, but it executes the block of code at least once before checking the condition.

let i = 0;
do {
  console.log(i); // 0, 1, 2, 3, 4
  i++;
} while (i < 5);

In the above example, the loop runs at least once and continues while i is less than 5.

Highlighting differences

• for loop is best when the number of iterations is known.
• while loop is useful when the number of iterations is not known and depends on a condition.
• do...while loop ensures the code block runs at least once.

for (let i = 0; i < 3; i++) {
  console.log(i); // 0, 1, 2
}
 
let j = 0;
while (j < 3) {
  console.log(j); // 0, 1, 2
  j++;
}
 
let k = 0;
do {
  console.log(k); // 0, 1, 2
  k++;
} while (k < 3);

When to use different loops

Use for loop when you know the exact number of iterations. Use while loop when the number of iterations depends on a condition. Use do...while loop when you need to ensure the code block runs at least once.

for (let i = 0; i < 10; i++) {
  console.log(i); // Use for loop for known iterations
}
 
let condition = true;
while (condition) {
  // Use while loop for condition-based iterations
  condition = false;
}
 
do {
  // Use do...while loop to run code at least once
} while (false);

Conclusion

Understanding the differences between various loops in JavaScript is crucial for writing efficient and readable code. Use the appropriate loop based on your specific needs.

Happy coding!