BBS Post Link Preview

// ==UserScript==
// @name             BBS Post Link Previews
// @namespace        dollars-bbs.org
// @author           Degritone
// @description      Allows you to hover over a >> link for a preview of the post
// @match            *://*.dollars-bbs.org/*
// @grant            none
// ==/UserScript==

function request(url){
  let xmlHttp = new XMLHttpRequest();
  xmlHttp.open("GET",url,false);
  xmlHttp.send(null);
  return xmlHttp.responseText;
}

function work(){
  let replies = document.getElementsByClassName("replytext");
  if(!replies){
    setTimeout(work,100);
    return;
  }
  setTimeout(work,500);
  for(let i=0;i<replies.length;i++){
    let as = replies[i].getElementsByTagName("a");
    for(let j=0;j<as.length;j++){
      if(as[j].href.startsWith("https://dollars-bbs.org") && as[j].href.match(/#[0-9]+$/)){
        if(as[j].class == "" || !as[j].class){
          as[j].setAttribute("class","postPreview");
          as[j].addEventListener("mouseenter",preview,false);
        }
      }
    }
  }
}

function preview(e){
  while(document.getElementById("previewPost"))
    document.getElementById("previewPost").parentNode.removeChild(document.getElementById("previewPost"));

  let parser = new DOMParser();
  let page = parser.parseFromString(request(e.currentTarget.href),"text/html");
  let target = e.currentTarget.href.match(/#[0-9]+$/)[0].replace("#","");
  let post = page.getElementById(target).parentNode.parentNode.parentNode;
  document.body.appendChild(post);
  post.id = "previewPost";
  post.class = "replytext";
  post.style.position = "fixed";
  post.style.topMargin = "auto";
  post.style.bottomMargin = "auto";
  post.style.rightMargin = "0px";
  post.style.width = (600)+"px";
  post.style.backgroundColor = "#4D4D4D";
  post.style.border = "solid #EEEEEE 1px";
  post.style.borderRadius = "7px";
  post.style.fontSize = "13px";
  post.style.overflowY = "auto";
  post.style.maxHeight = ""+(window.innerHeight-2)+"px";78

  post.getElementsByClassName("replynum")[0].parentNode.style.fontWeight = "normal";
  post.getElementsByClassName("replynum")[0].parentNode.style.fontSize = "13px";
  post.getElementsByClassName("replynum")[0].parentNode.style.marginLeft = "5px";
  post.getElementsByClassName("replynum")[0].parentNode.style.width = "590px";
  post.getElementsByClassName("replynum")[0].parentNode.style.marginTop = "5px";

  post.getElementsByClassName("replynum")[0].getElementsByTagName("a")[0].style.textDecoration = "none";
  post.getElementsByClassName("replynum")[0].getElementsByTagName("a")[0].style.fontWeight = "bold";
  post.getElementsByClassName("postername")[0].style.fontSize = "16px";
  post.getElementsByClassName("postername")[0].style.fontWeight = "bold";
  post.getElementsByClassName("postertrip")[0].style.fontSize = "16px";
  post.getElementsByClassName("postertrip")[0].style.fontStyle = "italic";

  if(post.getElementsByTagName("img").length>0){
    let imgdiv = document.createElement("div");
    post.getElementsByTagName("h3")[0].after(imgdiv);
    imgdiv.appendChild(post.getElementsByTagName("img")[0].parentNode);
    imgdiv.style.margin = "auto";
    imgdiv.style.width = "500px";
    imgdiv.style.border = "1px solid #EEEEEE";
  }

  let as = post.getElementsByClassName("replytext")[0].getElementsByTagName("a");
  for(let i=0;i<as.length;i++){
    if(as[i].href.startsWith("https://dollars-bbs.org") && as[i].href.match(/#[0-9]+$/)){
      as[i].addEventListener("mouseenter",preview,false);
    }
  }

  let width = 600+((post.offsetHeight>=parseInt(post.style.maxHeight.replace("px","")))?15:0);
  post.style.width = width+"px";
  post.style.right = "1px";
  post.style.top = ""+((window.innerHeight-post.offsetHeight)/2+1)+"px";
  post.addEventListener("mouseup",(e)=>{e.stopPropagation();});
}

function remove(){
  while(document.getElementById("previewPost"))
    document.getElementById("previewPost").parentNode.removeChild(document.getElementById("previewPost"));
}

work();
document.addEventListener("mouseup",remove,false);