J5 - JavaScript can't find variable "strokeCap"

Question

I'm trying to get into generative Art and using for the first time p5.js for that. Now, I've tried to follow a guide to understand the process. I did exactly how the guide told me to do so, now I'm trying to figure out why I do have an error. The error is "ReferenceError: Can't find variable: strokeCap" I'm not really sure, why it does say can't find variable. Please help me out! I'd be very thankful.

function setup() {
  createCanvas(400, 400);
  noLoop()
  colorMode(HSL)
}

function draw() {
  background("antiquewhite");
}
 let loops = 5;
 while (loops--) {
    strokeCap(SQUARE);
  strokeWeight(random(50));
  stroke(random(0, 50), random(0, 100), random(0, 100));
  line(random(50,350),random(50,350),random(50,350),random(50,350));
}

function mousePressed(){
  saveCanvas("outputSave","png")
}