JavaScript Program to Print Pyramid Pattern by using Numbers
A pyramid pattern using numbers is a sequence of numbers arranged in a triangular shape, with each row displaying incrementing or decrementing numbers, creating a visually structured pattern.
Example:
1
1 2 3
1 2 3 4 5
1 2 3 4 5 6 7
1 2 3 4 5 6 7 8 9
Approach
- We initialize a variable n with the value 5. This variable determines the number of rows in the pattern.
- We use a for loop with the variable i to iterate from 1 to n (inclusive). This loop controls the rows of the pattern.
- Inside the outer loop, there’s another for loop with the variable j, iterating from 1 to 2 * n (twice the number of columns). This loop controls the columns of the pattern.
- we use Conditional logic to checks if (i + j >= n + 1 && i >= j – n + 1) for number or gap. Numbers increment; otherwise, two spaces are added.
- After the inner loop, print str (one row). Repeat for each i, forming the desired pattern.
Example 1: We are using the above-explained approach.
Javascript
let n = 5; for (let i = 1; i <= n; i++) { let str = '' ; let count = 1; for (let j = 1; j <= 2 * n; ++j) { if (i + j >= n + 1 && (i >= j - n + 1)) { // Add a space after each number str += count.toString() + ' ' ; count++; } else { // Add two spaces for the gap str += ' ' ; } } console.log(str); } |
Output
1 1 2 3 1 2 3 4 5 1 2 3 4 5 6 7 1 2 3 4 5 6 7 8 9
Example 2: We are making Pyramid pattern by using number in left direction.
Javascript
let n = 5; for (let i = 1; i <= n; i++) { let str = '' ; let count = 1; for (let j = 1; j <= n; ++j) { if (i + j >= 1 + n && j <= n) { // Add a space after each number str += count.toString() + ' ' ; count += 1; } else { // Add two spaces for the gap str += ' ' ; } } console.log(str); }; for (let i = n - 1; i >= 1; i--) { let str = '' ; let count = 1; for (let j = 1; j <= n; ++j) { if (i + j >= 1 + n && j <= n) { // Add a space after each number str += count.toString() + ' ' ; count += 1; } else { // Add two spaces for the gap str += ' ' ; } } console.log(str); }; |
Output
1 1 2 1 2 3 1 2 3 4 1 2 3 4 5 1 2 3 4 1 2 3 1 2 1
Example 3: We are making Pyramid pattern by using numbers in right direction.
Javascript
let n = 5; for (let i = 1; i <= n; i++) { let str = "" ; let count = 1; // Add numbers for (let k = 1; k <= i; k++) { str = count.toString() + " " + str; count += 1; } // Add spaces after numbers for (let j = i; j < n; j++) { str += " " ; } console.log(str); } for (let i = n - 1; i >= 1; i--) { let str = "" ; let count = 1; // Add numbers for (let k = 1; k <= i; k++) { str = count.toString() + " " + str; count += 1; } // Add spaces after numbers for (let j = i; j < n; j++) { str += " " ; } console.log(str); }; |
Output
1 2 1 3 2 1 4 3 2 1 5 4 3 2 1 4 3 2 1 3 2 1 2 1 1
Example 4: We are generated number pyramid in down-ward direction.
Javascript
let n = 5; for (let i = n; i >= 1; i--) { let str = '' ; let count = 1; for (let j = 1; j <= 2 * n; ++j) { if (i + j >= n + 1 && (i >= j - n + 1)) { // Add a space after each number str += count.toString() + ' ' ; count++; } else { // Add two spaces for the gap str += ' ' ; } } console.log(str); }; |
Output
1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 1 2 3 4 5 1 2 3 1
Example 5: We are generating Inverted Half Pyramid
Javascript
function printInvertedHalfPyramid(rows) { for (let i = rows; i >= 1; i--) { let row = '' ; for (let j = 1; j <= i; j++) { row += j + ' ' ; } console.log(row); } } // Example usage for an inverted half pyramid with 5 rows printInvertedHalfPyramid(5); |
Output
1 2 3 4 5 1 2 3 4 1 2 3 1 2 1