Wikipedia preview

Shows previews for Wikipedia links inline

You will need to install an extension such as Tampermonkey, Greasemonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Userscripts to install this script.

You will need to install an extension such as Tampermonkey to install this script.

You will need to install a user script manager extension to install this script.

(I already have a user script manager, let me install it!)

You will need to install an extension such as Stylus to install this style.

You will need to install an extension such as Stylus to install this style.

You will need to install an extension such as Stylus to install this style.

You will need to install a user style manager extension to install this style.

You will need to install a user style manager extension to install this style.

You will need to install a user style manager extension to install this style.

(I already have a user style manager, let me install it!)

// ==UserScript==
// @name        Wikipedia preview
// @description Shows previews for Wikipedia links inline
// @version     1.1
// @grant       GM.xmlHttpRequest
// @namespace   https://greasyfork.org/users/223733
// @match       *://*/*
// @run-at      document-start
// @connect     wikipedia.org
// ==/UserScript==

const regex = /^https?:\/\/(?:[a-z]+\.)wikipedia.org\/wiki\/(.+)/;
const apiReqBase = "https://en.wikipedia.org/api/rest_v1/page/summary/";

function fetchJson(url) {
	return new Promise(yay => {
  	GM.xmlHttpRequest({
    	method: "GET",
      url,
      onload(response) {
      	yay(JSON.parse(response.responseText));
      }
    });
  });
}

function attachToLink(link) {
    let timeout, mouseX, mouseY;
    link.addEventListener("mousemove", e => {
        mouseX = e.pageX;
        mouseY = e.pageY;
    });
    link.addEventListener("mouseover", () => {
        timeout = setTimeout(function() {
            const fn = async () => {
                const urlName = regex.exec(link.href)[1];
                const data = await fetchJson(apiReqBase + urlName);

                const container = document.createElement("a");
                container.href = data.content_urls.desktop.page;
                container.style.display = "block";
                container.style.position = "absolute";
                container.style.top = (mouseY - 10) + "px";
                container.style.left = (mouseX - 10) + "px";
                container.style.background = "white";
                container.style.borderRadius = "10px";
                container.style.boxShadow = "0 0 3px 0 #0007";
                container.style.overflowX = "hidden";
                container.style.overflowY = "auto";
                container.style.textDecoration = "none";
                container.style.width = "30vw";

                const title = document.createElement("h3");
                title.textContent = data.title;
                title.style.fontFamily = "sans-serif";
                title.style.fontWeight = "bold";
                title.style.fontSize = "1.3em";
                title.style.color = "black";
                title.style.padding = "1em 1.3em";
                title.style.borderBottom = "1px solid black";

                const image = document.createElement("img");
                image.style.width = "30vw";
                image.style.borderBottom = "1px solid grey";
              	image.onerror = () => {
                  console.log("error");
                	const cspError = document.createElement("p");
                  cspError.textContent = "Your browser won't let us load this image";
                  cspError.style.textAlign = "center";
                  cspError.style.fontFamily = "sans-serif";
                  cspError.style.color = "grey";
                  cspError.style.fontSize = ".8em";
                  cspError.style.padding = "1em 1.3em";
                  image.replaceWith(cspError);
                };
                image.src = data.originalimage && data.originalimage.source;

                const text = document.createElement("div");
                text.innerHTML = data.extract_html;
                text.style.color = "black";
                text.style.fontFamily = "sans-serif";
                text.style.padding = "1em 1.3em";

                container.appendChild(title);
                if (data.originalimage) container.appendChild(image);
                container.appendChild(text);
                document.body.appendChild(container);

                container.addEventListener("mouseout", () => {
                    container.remove();
                });
            };

            fn().catch(console.error);
        }, 200);
    });
    link.addEventListener("mouseout", () => clearInterval(timeout));
}

const mutationObserver = new MutationObserver(list => {
    Array.from(list)
        .map(el => el.target)
        .filter(el => regex.test(el.href))
        .forEach(attachToLink);
});

window.addEventListener("DOMContentLoaded", () => {
    const meta = document.createElement("meta");
    meta.setAttribute("http-equiv", "Content-Security-Policy");
    meta.setAttribute("content", "connect-src *");
    document.head.appendChild(meta);

    Array.from(document.querySelectorAll("a"))
        .filter(el => regex.test(el.href))
        .forEach(attachToLink);

    mutationObserver.observe(document.body, {
        attributes: true,
        childList: true,
        subtree: true
    });
});