🔁 Loops in JavaScript

Last Updated: Jan 2026

Loops allow us to repeat a block of code multiple times until a condition is met. They make our code short, clean, and powerful.

Why Use Loops?

Without loops 👇

printf("Hello");
printf("Hello");
printf("Hello");
printf("Hello");
printf("Hello");

With loops 👇

for (int i = 0; i < 5; i++) {
  printf("Hello");
}

💡 Less code, same result.

Loop Type	Used When
do...while	When you want to execute once before checking condition
while	When condition-based repetition is needed
for	When number of iterations is known

It will run once, even if the condition is false — because the condition is checked after the loop body.

Syntax:

do {
  // loop body
} while (condition);

int i = 0;
do {
  printf("%d\n",i);
  i++;
} while (i < 5);

💡 Output: Runs once (even though condition is false).

Repeats while the condition is true.

Syntax:

while (condition) {
  // loop body
}

int i = 1;

while (i <= 5) {
  printf("Count: %d\n", i);
  i++;
}

Repeats a specific number of times.

Syntax:

for (initialization; condition; update) {
  // code block
}

for (int i = 1; i <= 5; i++) {
  printf("Number: %d\n", i);
}