How to make a triangle using for loop javascript - Stack Overflow

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I have a simple question although i cannot manage to resolve this problem. Hope you can help. I need to make triangle using for loop and from this 4 exercises I don't know what to do with the third one. I haven't used Javascript before, so any help would be appreciated.

 # # # # #
   # # # #
     # # #     <----- here is triangle i need to make. Just in case 
       # #
         #

var i;
var j;
for (i = 0; i <= 5; i++ )
{
document.write("</br>");
for ( j = 0; j < 6-i; j++ )
{
document.write( "&nbsp&nbsp" );
}
for ( j = 6-i; j <= 5; j++ )
{

document.write( "*" );
}
}

I have a simple question although i cannot manage to resolve this problem. Hope you can help. I need to make triangle using for loop and from this 4 exercises I don't know what to do with the third one. I haven't used Javascript before, so any help would be appreciated.

 # # # # #
   # # # #
     # # #     <----- here is triangle i need to make. Just in case 
       # #
         #

var i;
var j;
for (i = 0; i <= 5; i++ )
{
document.write("</br>");
for ( j = 0; j < 6-i; j++ )
{
document.write( "&nbsp&nbsp" );
}
for ( j = 6-i; j <= 5; j++ )
{

document.write( "*" );
}
}

This is code I wrote for D in photo. And I'm sorry i did not add it at first.

• javascript
• for-loop
• triangle-count

Share Improve this question Follow edited Oct 28, 2016 at 10:37 ChrisB 2,58522 gold badges2626 silver badges4444 bronze badges asked Oct 27, 2016 at 20:07 Gevorg SahabalyanGevorg Sahabalyan 9211 gold badge11 silver badge88 bronze badges 2

• 1 You need to add what you've tried so far – Vasan Commented Oct 27, 2016 at 20:10
• Check out the how to ask... – Keno Commented Oct 27, 2016 at 20:12

Add a ment  | 

8 Answers 8

Sorted by: Reset to default 4

for (let line = "*"; line.length < 8; line += "*")
  console.log(line);

this question came in this book: http://eloquentjavascript

I don't know why there are so bad answers on google for this one.

function leftTriangle(rows){
  let result = '';
  for(let i=rows;i>0;i--){
    if(i===rows) {
      result += '*'.repeat(i) + '\n';
    }else{
      let empty = rows-i
      result+= ' '.repeat(empty) + '*'.repeat(i)+ '\n'
    }
  }
  return result;
}

console.log(leftTriangle(5))

I'm sure there are better solutions (simply left-padding with spaces es to mind), but here's the quick and dirty one I created from your own solution.

  for (var i = 0; i < 5; i++) {
    for (var j = 0; j < i; j++) {
      document.write("&nbsp;&nbsp;&nbsp;");
    }
    for (var j = 5; j > i; j--) {
      document.write("#");
      if (j > i + 1) document.write("&nbsp;");
    }
    document.write('<br/>')
  }

https://js.do/code/diamondsinthesky

Something like this?

var rows = 5;
for (var i = rows; i--;) {
  var columns = 0;
  while (columns <= i) {
    document.write('#');
    columns++
  }
  document.write('<br />\n');
}

Thank you for your help. I did it. It was too obvious but somehow I couldn't find it. Thank you one more time. Here is how i did it.

 for (i = 5; i > 0; i--) {
         document.write("</br>");
        for (j = 0; j < 6 - i; j++) {
            document.write("&nbsp&nbsp");
        }
        for (j = 6 - i; j <= 5; j++) {

            document.write("*");
        }
    }

var rows = 5;
for (var i = rows; i--;) {
  var columns = 0;
  while (columns <= i) {
    document.write('#');
    columns++
  }
  document.write('<br />\n');
}

You can also do this if you are looking for something different. This code is for a triangle of 7 lines.

let size = 8;
let y = "#";
for (let x = 0; x < size; x++)
{
  console.log(y);
  y += "#";
}

// Second method

for (let i = 1; i < size;i++)
{
  let me ="#".repeat(`${i}`)
  console.log(me);
  
}

  var size = 5;
    for (var i = 0; i < size; i++) {
       for (var j = 0; j <= i; j++) {
            document.write("*");
          }
          document.write("<br />\n");
        }

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