JavaScript Loops Explained Simply

In JavaScript, loops are used to repeat a block of code multiple times. Instead of writing the same code again and again, loops help you write clean, efficient, and readable code.

In this guide, you’ll learn:

What JavaScript loops are
Different types of loops
Real-world examples
Best practices and common mistakes

What Is a Loop in JavaScript?

A loop allows you to run the same code multiple times until a condition is met.

Loops are commonly used when:

Working with arrays
Displaying lists
Processing data
Handling repeated actions

Types of Loops in JavaScript

for loop
while loop
forEach loop

1. JavaScript `for` Loop

The for loop is used when you know how many times you want to run the loop.

Syntax


for (initialization; condition; increment) {
  // code to run
}

Example


for (let count = 1; count <= 5; count++) {
  console.log(count);
}

Explanation:

let count = 1 → starts the loop
count <= 5 → condition to continue
count++ → increases value after each run

Real-World Use Cases:

Pagination
Displaying numbered lists
Running fixed operations

2. JavaScript `while` Loop

The while loop runs as long as a condition is true.


let attempts = 1;

while (attempts <= 3) {
  console.log("Login attempt:", attempts);
  attempts++;
}

⚠️ Always ensure the condition eventually becomes false to avoid an infinite loop.

3. JavaScript `forEach` Loop

The forEach loop is used to iterate over arrays.


const colors = ["red", "green", "blue"];

colors.forEach(function (color) {
  console.log(color);
});

Arrow Function Version


colors.forEach((color) => {
  console.log(color);
});

Use Cases:

Rendering lists
Processing API data
Looping through UI elements

🎥 JavaScript Loop Video Tutorial

Want to see all of this in action with real examples? Watch our complete YouTube tutorial on JavaScript loops :

Common Loop Mistakes

❌ Infinite Loop


let i = 1;
while (i <= 5) {
  console.log(i);
}

✅ Correct Version


let i = 1;
while (i <= 5) {
  console.log(i);
  i++;
}

❌ Using `var`


for (var i = 0; i < 3; i++) {
  console.log(i);
}

✅ Best Practice


for (let i = 0; i < 3; i++) {
  console.log(i);
}

Best Practices for Writing Loops

Use meaningful variable names
Prefer let and const
Keep loops simple
Avoid deep nesting
Use forEach for arrays

When to Use Which Loop?

Loop Type	Best Use Case
for	Fixed number of iterations
while	Unknown number of repetitions
forEach	Looping through arrays

Conclusion

JavaScript loops are a core concept in web development. Mastering loops will make working with data and building dynamic websites much easier.

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JavaScript Loops Explained Simply | SR Programist