JSFiddle - React, Tailwind, and code Playground

HTML

<div id="output"></div>

JavaScript

var output = document.getElementById("output");

var sign = "#";

for(var k = 0; k < 2; k++){
  for (var i = 0; i <= 5; i++) {
    for (var j = 0; j <= i; j++) {
      output.innerHTML += sign;
    }
    output.innerHTML += "<br/>";
  }
}