根据评分最高的答案，但要在一行中定义日期:

const startToday = new Date(new Date().setUTCHours(0,0,0,0));
const endToday = new Date(new Date().setUTCHours(23,59,59,999));

解释:

new Date().setUTCHours(0,0,0,0) // returns the epoch time number
new Date(/* epoch number */) // returns that epoch Date object 

这就是为什么需要两个新的Date构造函数。

使用dayjs库，使用startOf和endOf方法，如下所示:

当地格林尼治时间:

const start = dayjs().startOf('day'); // set to 12:00 am today
const end = dayjs().endOf('day'); // set to 23:59 pm today

UTC的:

const utc = require('dayjs/plugin/utc');
dayjs.extend(utc);

const start = dayjs.utc().startOf('day'); 
const end = dayjs.utc().endOf('day'); 

使用(已弃用的)momentjs库，这可以通过startOf()和endOf()方法在时刻的当前日期对象上实现，将字符串'day'作为参数传递:

当地格林尼治时间:

var start = moment().startOf('day'); // set to 12:00 am today
var end = moment().endOf('day'); // set to 23:59 pm today

UTC的:

var start = moment.utc().startOf('day'); 
var end = moment.utc().endOf('day'); 

如果你对UTC时间的开始/结束感兴趣，你也可以使用模运算符:

const now = new Date().getTime();
let startOfDay = now - (now % 86400000);
let endDate = startOfDay + 86400000;

其中86400是一天的秒数，结果变量是Epoch(以毫秒为单位)。

如果你喜欢日期对象:

const now = new Date().getTime();
let startOfDay = new Date(now - (now % 86400000));
let endDate = new Date(now - (now % 86400000) + 86400000);

这可能有点棘手，但你可以使用Intl.DateTimeFormat。

下面的代码片段可以帮助您将任何时区的任何日期转换为开始/结束时间。

const beginingOfDay = (options = {}) => { const { date = new Date(), timeZone } = options; const parts = Intl.DateTimeFormat("en-US", { timeZone, hourCycle: "h23", hour: "numeric", minute: "numeric", second: "numeric", }).formatToParts(date); const hour = parseInt(parts.find((i) => i.type === "hour").value); const minute = parseInt(parts.find((i) => i.type === "minute").value); const second = parseInt(parts.find((i) => i.type === "second").value); return new Date( 1000 * Math.floor( (date - hour * 3600000 - minute * 60000 - second * 1000) / 1000 ) ); }; const endOfDay = (...args) => new Date(beginingOfDay(...args).getTime() + 86399999); const beginingOfYear = () => {}; console.log(beginingOfDay({ timeZone: "GMT" })); console.log(endOfDay({ timeZone: "GMT" })); console.log(beginingOfDay({ timeZone: "Asia/Tokyo" })); console.log(endOfDay({ timeZone: "Asia/Tokyo" }));

// get current time for UTC timezone
const d = new Date();
const year = d.getUTCFullYear();
const month = d.getUTCMonth();
const day = d.getUTCDate();
// set time to begin day UTC
const startTime = Date.UTC(year, month, day, 0, 0, 0, 0);
//set time to end day UTC
const endTime = Date.UTC(year, month, day, 23, 59, 0, 0);

我们可以用矩。

// for day start time
moment(moment().startOf('day')).format('HH:mm')

// for day end time
moment(moment().endOf('day')).format('HH:mm')