JavaScript Program to Print Numbers 1 to n

Use a for loop in JavaScript like for(let i = 1; i <= n; i++) { console.log(i); } to print numbers from 1 to n.

Examples

Input1

Output1

Input5

Output1 2 3 4 5

Input0

Output

How to Think About It

To print numbers from 1 to n, start counting from 1 and keep adding 1 until you reach n. For each number, show it on the screen. Stop when you reach n.

Algorithm

1

Get the input number n.

2

Start a counter i at 1.

3

While i is less than or equal to n, do the following:

4

Print the current value of i.

5

Increase i by 1.

6

Stop when i becomes greater than n.

Code

javascript

const n = 5;
for (let i = 1; i <= n; i++) {
  console.log(i);
}

Output

1
2
3
4
5

Dry Run

Let's trace the program with n = 3 to see how it prints numbers.

1

Initialize n and i

n = 3, i = 1

2

Check if i <= n

1 <= 3 is true, so print 1

3

Increment i

i becomes 2

4

Check if i <= n

2 <= 3 is true, so print 2

5

Increment i

i becomes 3

6

Check if i <= n

3 <= 3 is true, so print 3

7

Increment i

i becomes 4

8

Check if i <= n

4 <= 3 is false, stop loop

i	Condition i <= n	Action
1	true	Print 1
2	true	Print 2
3	true	Print 3
4	false	Stop

Why This Works

Step 1: Start from 1

We begin counting at 1 because the task is to print numbers starting from 1.

Step 2: Use a loop to repeat

The for loop repeats the printing action until the number reaches n.

Step 3: Stop after n

The loop stops when the number goes beyond n, ensuring only numbers 1 to n are printed.

Alternative Approaches

while loop

javascript

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

Uses a while loop instead of for; slightly longer but works the same.

recursive function

javascript

function printNumbers(i, n) {
  if (i > n) return;
  console.log(i);
  printNumbers(i + 1, n);
}
printNumbers(1, 5);

Uses recursion to print numbers; elegant but can cause stack issues for very large n.

Array and forEach

javascript

const n = 5;
Array.from({ length: n }, (_, i) => i + 1).forEach(num => console.log(num));

Creates an array and prints each number; less direct but shows array usage.

Complexity: O(n) time, O(1) space

Time Complexity

The loop runs from 1 to n, so it executes n times, making the time complexity O(n).

Space Complexity

The program uses a fixed amount of extra space regardless of n, so space complexity is O(1).

Which Approach is Fastest?

The simple for loop is fastest and most readable; recursion adds overhead and risk of stack overflow; array methods use extra memory.

Approach	Time	Space	Best For
For loop	O(n)	O(1)	Simple and efficient counting
While loop	O(n)	O(1)	Similar to for loop, slightly less concise
Recursive function	O(n)	O(n)	Elegant but risky for large n due to stack
Array with forEach	O(n)	O(n)	When working with arrays or functional style