$(document).ready(function() {
  if (
    typeof window.getComputedStyle(document.body).scrollBehavior === "undefined"
  ) {
    //判断浏览器是否支持scroll-behavior
    $("a.article").click(
      //给class为article的a标签赋予点击事件
      function() {
        $("html,body").animate(
          //令窗口滚动
          { scrollTop: $($(this).attr("href")).offset().top }, //滚动到当前点击的a标签的锚链接对应的位置
          { duration: 500, easing: "swing" } //滚动时间和滚动效果
        );
        return false;
      }
    );
  }
});

function scroll_to(Yposition) {
  if (
    typeof window.getComputedStyle(document.body).scrollBehavior === "undefined"
  ) {
    //判断浏览器是否支持scroll-behavior属性
    if (!window.requestAnimationFrame) {
      //判断浏览器是否支持requestAnimationFrame
      window.requestAnimationFrame = function(callback) {
        setTimeout(callback, 20);
      }; //本质是利用setTimeout来处理scrollTo函数(js是单线程,为了避免堵塞)
    } //如果不支持就手动定义(利用setTimeout)
    let scrollposition = pageYOffset; //得到窗口已滚动高度
    function smoothScroll() {
      //数字10代表了速度的衰减率,数字越小完成滚动的时间就越少
      let distance = Yposition - scrollposition;
      scrollposition = scrollposition + distance / 10;
      if (Math.abs(distance) < 1) {
        //如果距离小于1,结束递归函数
        window.scrollTo(0, Yposition);
      } else {
        window.scrollTo(0, scrollposition);
        requestAnimationFrame(smoothScroll);
      }
    }
    requestAnimationFrame(smoothScroll); //在smoothScroll函数里递归调用,直到距离小于1
  } else {
    //对于支持scroll-behavior属性的浏览器,直接执行scrollTo函数
    window.scrollTo(0, Yposition);
  }
}

function appear() {
  document.getElementById("sub_navigation_bar").style.right = "10px";
  setTimeout(function() {
    document.getElementById("sub_navigation_bar_button").onclick = disappear;
  }, 0);
}
function disappear() {
  document.getElementById("sub_navigation_bar").style.right = "-150px";
  setTimeout(function() {
    document.getElementById("sub_navigation_bar_button").onclick = appear;
  }, 0);
}

function text_appear(object) {
  //展开全文函数
  x = object.previousSibling; //上一个节点
  if (x.nodeType != 1) {
    x = x.previousSibling;
  }
  x.style.display = "block";
  y = x.previousSibling;
  if (y.nodeType != 1) {
    y = y.previousSibling;
  }
  y.style.display = "none";
  object.innerHTML = "收起全文";
  object.onclick = function() {
    text_disappear(object);
  };
}
function text_disappear(object) {
  //收起全文函数
  x = object.previousSibling;
  if (x.nodeType != 1) {
    x = x.previousSibling;
  }
  x.style.display = "none";
  y = x.previousSibling;
  if (y.nodeType != 1) {
    y = y.previousSibling;
  }
  y.style.display = "block";
  object.innerHTML = "展开全文";
  object.onclick = function() {
    text_appear(object);
  };
}