document.cookie="key=value";
//例
document.cookie="name=weiqi";

//可以在控制台中打印出cookie
console.log(document.cookie);

function getCookie(key){
  var index = document.cookie.indexOf(key);
  var returnValue;
  if(index!==-1){
    var tIndex = document.cookie.indexOf(";",index);
    var target = document.cookie.substring(index,tIndex);
    var returnValue = decodeURIComponent(target.replace(key+"=",""))
  }
  return returnValue;
}

document.cookie="name=weiqi";
getCookie("name"); //weiqi

function delCookie(key){
  var d = new Date();
  document.cookie=key+"=;expires="+ d.toGMTString();
}

document.cookie="name=weiqi";
delCookie("name"); //undefined

var d = new Date();
var time = 10;
d.setTime(d.getTime()+time*1000*60*60*24);
document.cookie="name=weiqi;expires="+ d.toGMTString();

//封装cookie方法的对象
var cookie = {
  setCookie:function(key,value,time){
    if(key == undefined){
      return;
    }
    if(time!== undefined){
      var d = new Date();
      d.setTime(d.getTime()+time*1000*60*60*24);
      document.cookie=key+"="+value+";expires="+ d.toGMTString();
    }else{
      document.cookie=key+"="+value;
    }
  },
  getCookie:function(key){
    var index = document.cookie.indexOf(key);
    var returnValue;
    if(index!==-1){
      var tIndex = document.cookie.indexOf(";",index);
      var target = document.cookie.substring(index,tIndex);
      var returnValue = decodeURIComponent(target.replace(key+"=",""))
     }
    return returnValue;
  },
  delCookie:function(key){
    var d = new Date();
    document.cookie=key+"=;expires="+ d.toGMTString();
  }
}


//测试
cookie.setCookie("home")
cookie.setCookie("name","卫旗");
cookie.setCookie("age",22);
cookie.setCookie("sex","男")
cookie.getCookie("sex")
cookie.delCookie("age")