V-Shaped Hollow Star Pattern in JavaScript
What You'll Learn
This program prints a hollow V (wide first row, legs meet at the bottom). See Program 7 for the inverted V. It uses for (let i = rows; i >= 1; i--) so the inner gap shrinks by 2 each row.
For each row, print leading spaces, a left edge star, an optional inner gap, and a right edge star.
⭐ Pattern Output
When you run the program with rows = 5:
* *
* *
* *
* *
*Complete JavaScript Program
Fixed rows = 5 version (reverse row loop):
const rows = 5;
for (let i = rows; i >= 1; i--) {
let line = "";
for (let s = 1; s <= rows - i; s++) line += " ";
line += "*";
if (i > 1) {
for (let g = 1; g <= 2 * i - 3; g++) line += " ";
line += "*";
}
console.log(line);
}🧠 How It Works
Setup
for (let i = rows; i >= 1; i--) prints the wide pair of legs first and ends at the bottom vertex. The same margin / first star / optional gap / second star structure as Program 7 applies; only i counts down.
Left margin and first star
for (let s = 1; s <= rows - i; s++) line += " "; then line += "*";. As i decreases, rows - i grows, shifting each row right.
Gap and second star
if (i > 1) appends 2 * i - 3 spaces in a loop, then the second *. When i === 1, only the first star runs—the bottom vertex.
Finish the line
console.log(line) ends each row. Line width stays 2 * rows - 1, same geometry as Program 7 with reversed row order.
Hollow V
Vertex at the bottom, opening upward. O(n²) output for n = rows, O(1) extra space. Combine with Program 7 for a full hollow diamond (Program 9).
💡 Tips for Enhancement
Try These
- Try Program 7 to print the inverted V (narrow top)
- Combine Program 7 and Program 8 to form a hollow diamond (Program 9)
- Increase
rowsto make a wider top row - Replace
*with a different character - Print with spaces between stars for a wider look
Avoid
- Printing a second star on the last row (it would duplicate the tip)
- Using tabs for alignment (rendering differs)
- Mixing
with normal spaces (output becomes inconsistent) - Forgetting to reverse the outer loop
- Forgetting the line break after each row
Key Takeaways
Reverse the row loop to start wide and narrow down.
Row prints rows - i leading spaces.
Two border stars form the hollow shape (except the final tip).
Inner gap is 2*i - 3 and shrinks by 2 each row.
Time complexity is O(n²) due to printing \(\Theta(n^2)\) characters.
❓ Frequently Asked Questions
i = 1..rows (narrow top). Program 8 reverses the outer loop (i = rows..1) so the wide row is first and the legs meet at the bottom vertex.n rows, since total printed characters are \(\Theta(n^2)\).Next: Hollow Diamond
Continue to Program 9 to combine Program 7 and Program 8 into a hollow diamond.
The same gap formula 2*i - 3 works in both directions; only the outer loop direction changes.
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