Triangle one loop

t.js

  var triangleSize;

  // Keep prompting for a valid positive number
  while (
    isNaN(triangleSize) ||
    typeof triangleSize !== 'number' ||
    triangleSize < 3 ||
    triangleSize % 1 != 0
  ) {
    triangleSize = parseInt(
      prompt('Enter the middle line of the triangle (a positive number 3 or higher):')
    );
  }

  var triangle = '\n';

  var count1 = 0; /**determine when to line break */
  var count2 = 1;
  var directionForward = true; /**determine when to extend or shorten lines*/
  var line = '';

  while (count2 != 0) {
    line += '*';
    count1++;
    if (triangleSize === count2) {
      directionForward = false;
    }

    if (count1 === count2) {
      directionForward ? count2++ : count2--;
      count1 = 0;
      triangle += line + '\n';
      line = '';
    }
  }
  console.log('🚀 ~ file: loops.js:284 ~ triangle', triangle);

For a use case where the render loop can only have one loop and no methods within