JavaScript Program to Print Pyramid Star Pattern

Namachila 14 hours ago

0 0 2 minutes read

In this article, we will demonstrate how to create pyramid star patterns in JavaScript.

The Possible Pyramid Star Patterns are:

Upper pyramid
Inverted pyramid
Left inverted pyramid
Right inverted pyramid

Approach

There will be two different approaches based on alignments i.e. horizontal and vertical.

Horizontally Inverted Pyramid

This type includes the upper pyramid and the inverted pyramid.
To achieve this we will use a javascript for loop to iterate N time
In that loop, print spaces repeat N-1 times before and after the start.
As the number of start changes by 2 in every line repeat the stars 2*i -1 times to get the required structure.

Vertically Inverted Pyramid

Vertically inverted pyramids include the Rigth inverted and Left inverted pyramids
To achieve this we will use Javascript for loop 2 time i.e. from 1 to N and back to 1.
In that loop, print spaces repeat N-i times before and after the start.
As the number of start changes by 1 in every line repeat the stars i times to get the required structure.

Example 1: Upper pyramid

Javascript

let n = 5; 
for (let i = 1; i <= n; i++) { 
    let str = "* "; 
    let space = '  '; 
    console.log(space.repeat((n - i)) + str.repeat(i * 2 - 1)); 
}

Output

        * 
      * * * 
    * * * * * 
  * * * * * * * 
* * * * * * * * *

Example 2: Inverted pyramid

Javascript

let n = 5; 
for (let i = n; i >= 1; i--) { 
    let str = "* "; 
    let space = '  '; 
    console.log(space.repeat((n - i)) + str.repeat(i * 2 - 1)); 
}

Output

* * * * * * * * * 
  * * * * * * * 
    * * * * * 
      * * * 
        *

Example 3: Left inverted pyramid

Javascript

let n = 5; 
for (let i = 1; i <= n; i++) { 
    let str = "* "; 
    let space = '  '; 
    console.log(space.repeat((n - i)) + str.repeat(i)); 
} 
  
for (let i = n - 1; i >= 1; i--) { 
    let str = "* "; 
    let space = '  '; 
    console.log(space.repeat(n - i) + str.repeat(i)); 
}

Output

        * 
      * * 
    * * * 
  * * * * 
* * * * * 
  * * * * 
    * * * 
      * * 
        *

Example 4: Right inverted pyramid

Javascript

let n = 5; 
for (let i = 1; i <= n; i++) { 
    let str = "* "; 
    console.log(str.repeat(i)); 
} 
for (let i = n - 1; i >= 1; i--) { 
    let str = "* "; 
    console.log(str.repeat(i)); 
}

Output

* 
* * 
* * * 
* * * * 
* * * * * 
* * * * 
* * * 
* * 
*

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