JavaScript Loops

Learn how to use loops in JavaScript to execute code repeatedly.

Introduction to Loops

Loops allow you to run the same block of code multiple times with different values. Making your program more efficient and concise.

Executes a block of code a specific number of times:


for (let i = 0; i < 5; i++) {
  console.log("Iteration " + i);
}

Executes as long as a condition is true:


let i = 0;
while (i < 5) {
  console.log("i is " + i);
  i++;
}

Executes at least once before checking the condition:


let i = 0;
do {
  console.log("Running once even if false");
  i++;
} while (i < 1);

Used to loop through elements in iterable objects like arrays:


let fruits = ["apple", "banana", "cherry"];
for (let fruit of fruits) {
  console.log(fruit);
}


for (let i = 1; i <= 5; i++) {
  if (i === 3) continue; // skip 3
  if (i === 5) break;    // stop at 5
  console.log(i);
}

Print the even numbers from 1 to 10 using a loop:


for (let i = 1; i <= 10; i++) {
  if (i % 2 === 0) {
    console.log(i);
  }
}