Pocket数を取得するためのJavaScript

get_pocket_count.js

async function get_pocket_count(url) {
  const pocketUrl = encodeURIComponent(`https://widgets.getpocket.com/v1/button?v=1&count=horizontal&url=${url}&src=${url}`);
  const response = await fetch(`http://query.yahooapis.com/v1/public/yql?q=select * from%20xml%20where%20url%3D%22${pocketUrl}%22&format=xml`)
  const str = await response.text();
  const doc = await new window.DOMParser().parseFromString(str, "text/xml")
  return doc.querySelector('#cnt').innerHTML;
}

こんな感じで取得できます。

get_pocket_count('https://appleple.github.io/SmartPhoto/').then(data => {console.log(data)});

chromeのpopupとの組み合わせ

chrome.tabs.query({'active': true, 'lastFocusedWindow': true}, function (tabs) {
  const url = tabs[0].url;
  get_pocket_count(url).then((data) => {
    document.querySelector('#count').innerHTML = data;
  });
});