createCanvas(400,400);

  background('black');

  let turtleString = "B";

  for (let i=0; i < 3; i++) {

   turtleString = turtleString.replaceAll("B","F[+B][-B]");

  }

  print(turtleString);

  stroke('white');

  strokeWeight(3);

  translate(width/2,height/2);

  renderString(turtleString);

}

​

let branchLength = 50;

let angle = Math.PI / 4;

​

function renderString(string) {

  for (let character of string) {

    if (character == 'F') {

      line(0, 0, 0, -branchLength);

      translate(0, -branchLength);

    } else if (character == '+') {

      rotate(angle);

    } else if (character == '-') {

      rotate(-angle);

    } else if (character == '[') {

      push();

    } else if (character == ']') {

      pop();

    }

  }

}