Cookie的新增，设置与清除

addCookieBtn.addEventListener('click',function () {
    document.cookie='imooc=www.imooc.com;expires=2016-07-20 10:10:10';
    content.innerHTML='cookie写入完成'
})
var getCookieBtn=document.getElementById('getCookieBtn');
getCookieBtn.addEventListener('click',function (ev) {
    content.inner="Cookie获取完成：<br/>"+document.cookie;
});
var clearCookBtn=document.getElementById('clearCookieBtn');
clearCookieBtn.addEventListener('click',function () {
    document.cookie="imooc=www.imo0oc.com;expires=2016-03-14 10:20:20";
    content.innerHTML="cookie清除完成"
})