JS BOM教程

//打开一个链接
window.open("www.baidu.com", "_self");

//清空页面，并写入东西
document.write("
");

window.navigator.userAgent

window.location = "www.baidu.com";

js制作侧边栏（跟随滚动）

window.resize = window.onload = window.onscroll = function() {
  var oDiv = document.getElementById("div1");
  //可视区顶部距离网页顶部的距离
  var scrollTop = document.documentElement.scrollTop || document.body.scrollTop;
  //(可视区的高度 - 物体本身高度)/2
  var t = (document.documentElement.clientHeight - oDiv.offsetHeight)/2;
//需要设置oDive 的position为absolute
oDiv.style.top = scrollTop + t +'px';
}
//此时拖动的时候有抖动现象
//设置position:fixed --> ie6不支持此固定定位

回到顶部按钮

window.load = function() {
  var timer = null;
  var bSys = true;
  
  windwo.onscroll = function() {
    if(!bSys) {
      clearinterval(timer);
    }
    bSys = false;
  }
  var oBtn = document.getElementById("btn1");
  oBtn.onclick = function() {
    timer = setInterval(function(){
      var scrollTop = document.documentElement.scrollTop || document.body.scrollTop;
      var iSpeed = Math.floor(-scrollTop / 8);
      if(scrollTop == 0) {
        clearInterval(timer);
      } 
      //系统滚动
      bSys = true;
      document.documentElement.scrollTop= document.body.scrollTop = scrollTop + iSpeed;
      }, 30);
  }

  window.onscroll
}