index_script.js

window.onscroll = function() {
  isScrolledIntoView(document.getElementById("all_petitions_list_cont"));
}

function isScrolledIntoView(elem) {
  var header = document.getElementById('header');
  var header_min = document.getElementById('header_min');
  var go_to_page_top = document.getElementById('go_to_page_top');

  var isMobile = window.innerWidth < 800;

  if (window.pageYOffset > elem.offsetTop) {
    header_min.style.display = "inline-block";

    var go_to_page_top = document.getElementById('go_to_page_top');

    go_to_page_top.style.display = "block";

    var footer = document.getElementsByTagName('footer')[0];

    var pageUpRect = go_to_page_top.getBoundingClientRect();
    var footerRect = footer.getBoundingClientRect();

    if (window.innerHeight > (footerRect.top + window.innerHeight - pageUpRect.bottom)) {
      go_to_page_top.style.background = "#eee";
      go_to_page_top.src = "ico/ic_expand_less_blue_24px.svg"
    } else {
      go_to_page_top.style.background = "#0277bd";
      go_to_page_top.src = "ico/ic_expand_less_white_24px.svg"
    }
    go_to_page_top.onclick = function() {
      // ANIMATION
      var a = window.pageYOffset;
      setInterval(function() {
        if (a > 0) {
          if (a > 100) {
            a -= (a / 100 + 100);
          } else {
            a -= 100;
          }

          window.scrollTo(0, a);
        } else {}
      }, 0);
    };

  } else if (isMobile) {
    header.style.display = "none";
    go_to_page_top.style.display = "none";
  } else {
    header.style.display = "inline-block";
    header_min.style.display = "none";
    go_to_page_top.style.display = "none";
  }
}

function loadAllPetitions() {

  var xmlHttp = new XMLHttpRequest();
  xmlHttp.onreadystatechange = function() {
    if (xmlHttp.readyState == 4 && xmlHttp.status == 200)
      AllPetitionsDataReceived(xmlHttp.responseText);
  }
  var url = "https://petition.parliament.uk/petitions.json";
  xmlHttp.open("GET", url, true); // true for asynchronous
  xmlHttp.send(null);
}

function AllPetitionsDataReceived(responseText) {
  var json = JSON.parse(responseText);
  var list = json.data;
  for (i = 0; i < list.length; i++) {
    var item = list[i];
    if (item.type == "petition") {
      var el = document.createElement("p");
      el.innerHTML = "<b>" + item.attributes.action + "</b><br/> <p class=all_petitions_list_item_p style='margin-bottom:0;'><i> by " + item.attributes.creator_name + "</i></p>";
      el.className = "all_petitions_list_item";
      el.onclick = (function(i) {
        return function() {
          //var purl = list[i].links.self;
          var purl = "petition.html?p=" + list[i].id;

          window.location.href = purl;
        }
      })(i);
      if (item.attributes.government_response != null) {
        el.style.borderLeft = "5px solid green";
      } else {
        el.style.borderLeft = "5px solid red";
      }
      document.getElementById('all_petitions_list_cont').appendChild(el);
    }

  }

  document.getElementById('loading').style.display = "none";
  document.getElementById('main_div').style.display = "block";
}

window.onload = function() {
  loadAllPetitions();
}