chrome.tabs.onUpdated.addListener(function(tabId,changeInfo,tab) {
    if(changeInfo.url){
     console.log("tab url changed");
    chrome.tabs.executeScript(null, {file: "js/jquery-3.2.1.min.js"});
         chrome.tabs.executeScript(null, {file: "payload.js"});
        }

});

console.log("ready");
     $(document).ready(function() {
     var button = document.getElementsByClassName("recommend u-flexColumn u-marginBottom10 u-width60")[0];
     if (button) {
      console.log("element is ready");
     }
     });

chrome.tabs.onUpdated.addListener(function(tabId, changeInfo, tab) {
  if (changeInfo.url) {
      console.log("tab url changed");
      chrome.tabs.executeScript(tabId, {file: "js/jquery-3.2.1.min.js"});
      chrome.tabs.executeScript(tabId, {file: "payload.js"});
  }
});