JSFiddle - React, Tailwind, and code Playground
by mo nagano
HTML
<select id="selectbox">
<option value="">予約日を選択してください</option>
</select>
JavaScript
var selectElement = document.getElementById("selectbox");
var today = new Date();
var loop = 40;
var year, month, day, yobi_num, yobi, ans;
today.setDate(today.getDate() + 7);//7日後
for(var i =0 ;i<loop;i++){
year = today.getFullYear();
month = today.getMonth()+1;
day = today.getDate();
yobi_num = today.getDay();
yobi = new Array("日","月","火","水","木","金","土");
ans = year +"/" + month + "/" + day + "(" + yobi[yobi_num] +")";
// console.log(ans);
today.setDate(day + 1);
var element = document.createElement("option");
element.innerText = ans;
element.value = ans;
selectElement.appendChild(element);
}