将日期和时间添加到隐藏输入值

<input type="hidden" id="datetime" name="datetime" value="">

var currentDate = new Date();
var year = currentDate.getFullYear();
var month = ("0" + (currentDate.getMonth() + 1)).slice(-2);
var day = ("0" + currentDate.getDate()).slice(-2);
var hours = ("0" + currentDate.getHours()).slice(-2);
var minutes = ("0" + currentDate.getMinutes()).slice(-2);
var seconds = ("0" + currentDate.getSeconds()).slice(-2);

var datetimeValue = year + "-" + month + "-" + day + " " + hours + ":" + minutes + ":" + seconds;

document.getElementById("datetime").value = datetimeValue;