Welcome to JavaScript loops! Loops are fundamental control structures that allow you to execute a block of code repeatedly. Instead of writing the same code multiple times, loops help you automate repetitive tasks and efficiently iterate over data collections like arrays or objects. Let's explore how loops work with this simple counting example.
The for loop is the most common loop in JavaScript. It consists of three parts: initialization where you set the starting value, condition that determines when to stop, and increment that updates the counter. This structure makes it perfect for situations where you know exactly how many times you want to repeat code, or when you need to iterate through arrays using index numbers.
While loops and do-while loops are condition-based loops. The while loop checks the condition first, then executes the code block if true. It's perfect when you don't know how many iterations you need. The do-while loop is similar, but it guarantees the code runs at least once because it checks the condition after execution. Both loops depend on changing variables within the loop to eventually make the condition false.
JavaScript provides two specialized loops for different iteration needs. The for...in loop iterates over object properties, making it perfect for objects but risky for arrays due to inherited properties. The for...of loop iterates over values of iterable objects like arrays, strings, Maps, and Sets. It's the modern, preferred way to loop through array elements because it's cleaner and avoids index-related issues.
Loop control statements give you precise control over loop execution. The break statement immediately exits the entire loop, useful when you've found what you're looking for or met a stopping condition. The continue statement skips only the current iteration and moves to the next one, perfect for filtering out unwanted values. These statements make your loops more efficient and help handle special cases elegantly.