javascript - 使用本地日期设置和获取 HTMLInputElement.valueAsDate 的正确方法是什么？

Question

valueAsDate 的功能似乎存在根本性缺陷:

var date1 = new Date();
date1 = new Date(date1.getFullYear(), date1.getMonth(), date1.getDate()); // input expects requires year, month, day

var input = document.createElement("input"); input.type = "date";

input.valueAsDate = date1;

var date2 = input.valueAsDate;

console.log(date1);
console.log(date2);

console.log(date1.getTime(), date2.getTime()); // EVEN THE UTC TIMESTAMP IS NOT EQUAL!!

我想设置一个本地日期，我想获取一个本地日期。如何在来回保持正确的日期类型(UTC 或本地)的同时始终实现这一点？

Answer 1

<input type="date"> 上显示的日期是 UTC 天数。如果你想把它们当作本地的日子，你需要调整 Date对象:

var date1 = new Date(); // now
var input = document.createElement("input"); input.type = "date";

input.valueAsDate = new Date(Date.UTC(date1.getFullYear(), date1.getMonth(), date1.getDate()));

var midnightUtcDate = input.valueAsDate;
var date2 = new Date(midnightUtcDate.getUTCFullYear(), midnightUtcDate.getUTCMonth(), midnightUtcDate.getUTCDate());

console.log(date1, date1.toLocaleDateString());
console.log(date2, date2.toLocaleDateString());