知乎防火星

.user.js

// ==UserScript==
// @name     知乎防火星
// @version  1
// @grant    none
// @include  /^https?://www\.zhihu\.com/.*$/
// ==/UserScript==

const WARNING_HTML = (x)=>`<div class="QuestionStatus"><div class="QuestionStatus-bar"><div class="QuestionStatus-bar-inner" style="background-color:red;"><strong>这个问题是${x}前提问的！</strong><em>提问内容可能已过时或不适用于当下</em><div class="ztext" style="color:white;">转发时请注意自己别火星了</div></div></div><div><span style="position: absolute; top: -10000px; left: -10000px;" role="log" aria-live="assertive"></span></div><div><span style="position: absolute; top: -10000px; left: -10000px;" role="log" aria-live="assertive"></span></div></div>`

function createWarningTag(tag){
  var div = document.createElement('div');
  div.innerHTML = WARNING_HTML(tag).trim();

  // Change this to div.childNodes to support multiple top-level nodes.
  return div.firstChild;
}

function smartDate(x){
  x=Math.round(x);
  let unit = 1000*60*60*24*30*12;
	let s = "";
  s+=(x>=unit? `${Math.floor(x/unit)}年`: "");
  x=x%unit; unit/=12;
  s+=(x>=unit? `${Math.floor(x/unit)}个月`: "");
  x=x%unit; unit/=30;
  s+=(x>=unit? `${Math.floor(x/unit)}天`: "");
  x=x%unit; unit/=24;
  s+=(x>=unit? `${Math.floor(x/unit)}小时`: "");
  x=x%unit; unit/=60;
  return s;
}

const f = (()=>{
  const createTime = document.querySelector("meta[itemprop='dateCreated']");
  if(!createTime) return;
  const delta = (new Date() - new Date(createTime.content));
	if(delta>=30*24*60*60*1000){
  	document.querySelector('div[data-za-detail-view-path-module="QuestionDescription"]').parentNode.prepend(createWarningTag(`${smartDate(delta)}`))
  }  
})

window.addEventListener('load', f, false);