<button onclick="setCookie('username','John',1)">setCookie</button>
<button onclick="getCookie('username')">getCookie</button>
<button onclick="removeCookie('username')">moveCookie</button>

JS：

function setCookie(key, value, t){
	var oDate=new Date();
	oDate.setDate(oDate.getDate()+t);
	document.cookie=key+"="+encodeURIComponent(value)+";expires="+oDate.toUTCString();
	if(getCookie(key)){
		alert('設定成功');
	}else{
		alert('設定失敗');
	}
}
function getCookie(key){
	var str=document.cookie.replace(/;\s*/,';');
	var cookieArr=str.split(';');
	var cookieObj={};
	var len=cookieArr.length;
	for(var i=0; i<len; i++){
		var item=cookieArr[i];
		var k=item.split('=')[0];
		var v=item.split('=')[1];
		cookieObj[k]=v;
	}
	if(cookieObj[key]){
		return decodeURIComponent(cookieObj[key]);
	}else{
		return false;
	}
}
function removeCookie(key){
	document.cookie=key+"=; expires=Thu, 01 Jan 1970 00:00:00 GMT";
	if(!getCookie(key)){
		alert('刪除成功');
	}else{
		alert('刪除失敗');
	}
}
console.log(getCookie('username'))