JavaScript Loops

JavaScript loops are fundamental control structures that allow developers to execute a block of code repeatedly. There are primarily three types of loops in JavaScript: for, while, and do...while. Below, a detailed explanation of each type with examples:

For Loop

The for loop iterates over a range of values using an index variable. It consists of three parts: initialization, condition, and iteration.

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

While Loop

The while loop repeats a block of code as long as a specified condition remains true.

let count = 0; while (count < 3) { console.log(count); // Output: 0, 1, 2 count++; }

Do...While Loop

The do...while loop is similar to the while loop, but it ensures that the loop block is executed at least once before checking the condition.

let num = 5; do { console.log(num); // Output: 5 num--; } while (num > 0);

Loop Control Statements

JavaScript provides loop control statements to modify the loop's behavior:

  1. break: Exits the loop prematurely.
  2. continue: Skips the rest of the current iteration and proceeds to the next.
for (let i = 0; i < 5; i++) { if (i === 3) { break; // Loop exits when i is 3 } console.log(i); // Output: 0, 1, 2 } for (let i = 0; i < 5; i++) { if (i === 2) { continue; // Skips printing 2 } console.log(i); // Output: 0, 1, 3, 4 }

Looping Through Arrays

Loops are commonly used to iterate through arrays:

let colors = ["red", "green", "blue"]; for (let i = 0; i < colors.length; i++) { console.log(colors[i]); // Output: "red", "green", "blue" }

For...of Loop (ES6)

The for...of loop simplifies iterating through arrays and other iterable objects.

let numbers = [1, 2, 3]; for (let num of numbers) { console.log(num); // Output: 1, 2, 3 }

Conclusion

JavaScript loops are essential for automating repetitive tasks, such as iterating through collections, validating conditions, and executing actions multiple times, enhancing the efficiency and functionality of your code.






Related Topics
  1. JavaScript Data Types and Variables
  2. Arrays in JavaScript
  3. JavaScript string
  4. JavaScript If...Else Statements
  1. Global Variables in JavaScript
  2. Working with JavaScript objects
  3. JavaScript Functions
  4. JavaScript Date Formats