如何将字符串转换为JavaScript日期对象?
var st = "date in some format"
var dt = new Date();
var dt_st = // st in Date format, same as dt.
当前回答
你可以试试这个:
function formatDate(userDOB) { const dob = new Date(userDOB); const monthNames = [ 'January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December' ]; const day = dob.getDate(); const monthIndex = dob.getMonth(); const year = dob.getFullYear(); // return day + ' ' + monthNames[monthIndex] + ' ' + year; return `${day} ${monthNames[monthIndex]} ${year}`; } console.log(formatDate('1982-08-10'));
其他回答
Var a = "13:15" var b = toDate(a， "h:m") / /警报(b); document . write (b); 函数toDate(dStr, format) { var now = new Date(); If (format == "h:m") { now.setHours(下游。substr (0, dStr.indexOf(“:”))); now.setMinutes(dStr.substr(dStr.indexOf(":") + 1)); now.setSeconds (0); 现在返回; 其他} 返回“格式无效”; ｝
我已经创建了parseDateTime函数将字符串转换为日期对象，它在所有浏览器(包括IE浏览器)中工作，检查是否有人需要，引用 https://github.com/Umesh-Markande/Parse-String-to-Date-in-all-browser
function parseDateTime(datetime) {
var monthNames = [
"January", "February", "March",
"April", "May", "June", "July",
"August", "September", "October",
"November", "December"
];
if(datetime.split(' ').length == 3){
var date = datetime.split(' ')[0];
var time = datetime.split(' ')[1].replace('.00','');
var timearray = time.split(':');
var hours = parseInt(time.split(':')[0]);
var format = datetime.split(' ')[2];
var bits = date.split(/\D/);
date = new Date(bits[0], --bits[1], bits[2]); /* if you change format of datetime which is passed to this function, you need to change bits e.x ( bits[0], bits[1], bits[2 ]) position as per date, months and year it represent bits array.*/
var day = date.getDate();
var monthIndex = date.getMonth();
var year = date.getFullYear();
if ((format === 'PM' || format === 'pm') && hours !== 12) {
hours += 12;
try{ time = hours+':'+timearray[1]+':'+timearray[2] }catch(e){ time = hours+':'+timearray[1] }
}
var formateddatetime = new Date(monthNames[monthIndex] + ' ' + day + ' ' + year + ' ' + time);
return formateddatetime;
}else if(datetime.split(' ').length == 2){
var date = datetime.split(' ')[0];
var time = datetime.split(' ')[1];
var bits = date.split(/\D/);
var datetimevalue = new Date(bits[0], --bits[1], bits[2]); /* if you change format of datetime which is passed to this function, you need to change bits e.x ( bits[0], bits[1], bits[2 ]) position as per date, months and year it represent bits array.*/
var day = datetimevalue.getDate();
var monthIndex = datetimevalue.getMonth();
var year = datetimevalue.getFullYear();
var formateddatetime = new Date(monthNames[monthIndex] + ' ' + day + ' ' + year + ' ' + time);
return formateddatetime;
}else if(datetime != ''){
var bits = datetime.split(/\D/);
var date = new Date(bits[0], --bits[1], bits[2]); /* if you change format of datetime which is passed to this function, you need to change bits e.x ( bits[0], bits[1], bits[2 ]) position as per date, months and year it represent bits array.*/
return date;
}
return datetime;
}
var date1 = '2018-05-14 05:04:22 AM'; // yyyy-mm-dd hh:mm:ss A
var date2 = '2018/05/14 05:04:22 AM'; // yyyy/mm/dd hh:mm:ss A
var date3 = '2018/05/04'; // yyyy/mm/dd
var date4 = '2018-05-04'; // yyyy-mm-dd
var date5 = '2018-05-14 15:04:22'; // yyyy-mm-dd HH:mm:ss
var date6 = '2018/05/14 14:04:22'; // yyyy/mm/dd HH:mm:ss
console.log(parseDateTime(date1))
console.log(parseDateTime(date2))
console.log(parseDateTime(date3))
console.log(parseDateTime(date4))
console.log(parseDateTime(date5))
console.log(parseDateTime(date6))
**Output---**
Mon May 14 2018 05:04:22 GMT+0530 (India Standard Time)
Mon May 14 2018 05:04:22 GMT+0530 (India Standard Time)
Fri May 04 2018 00:00:00 GMT+0530 (India Standard Time)
Fri May 04 2018 00:00:00 GMT+0530 (India Standard Time)
Mon May 14 2018 15:04:22 GMT+0530 (India Standard Time)
Mon May 14 2018 14:04:22 GMT+0530 (India Standard Time)
这个答案是基于卡塞姆的答案，但它也适用于两位数的年份。我对卡塞姆的答案进行了编辑，但以防它没有被批准，我还将这个作为单独的答案提交。
function stringToDate(_date,_format,_delimiter) {
var formatLowerCase=_format.toLowerCase();
var formatItems=formatLowerCase.split(_delimiter);
var dateItems=_date.split(_delimiter);
var monthIndex=formatItems.indexOf("mm");
var dayIndex=formatItems.indexOf("dd");
var yearIndex=formatItems.indexOf("yyyy");
var year = parseInt(dateItems[yearIndex]);
// adjust for 2 digit year
if (year < 100) { year += 2000; }
var month=parseInt(dateItems[monthIndex]);
month-=1;
var formatedDate = new Date(year,month,dateItems[dayIndex]);
return formatedDate;
}
stringToDate("17/9/14","dd/MM/yyyy","/");
stringToDate("17/9/2014","dd/MM/yyyy","/");
stringToDate("9/17/2014","mm/dd/yyyy","/")
stringToDate("9-17-2014","mm-dd-yyyy","-")
性能
今天(2020.05.08)，我对所选解决方案进行了测试-有两种情况:输入日期是ISO8601字符串(Ad,Bd,Cd,Dd,Ed)，输入日期是时间戳(At, Ct, Dt)。解决方案Bd,Cd,Ct不返回js Date对象作为结果，但我添加它们，因为它们可能是有用的，但我没有将它们与有效的解决方案进行比较。该结果对于大量数据解析非常有用。
结论
解决方案new Date (Ad)比moment.js (Dd)快50-100倍，适用于所有浏览器的ISO日期和时间戳 解决方案new Date (Ad)比parseDate (Ed)快10倍 解决方案date .parse(Bd)是最快的，如果我们需要在所有浏览器上从ISO日期获得时间戳
细节
我在MacOs High Sierra 10.13.6、Chrome 81.0、Safari 13.1、Firefox 75.0上进行测试。解决方案parseDate (Ed)使用新的Date(0)和手动设置UTC日期组件。
let ds = '2020-05-14T00:00Z'; // Valid ISO8601 UTC date let ts = +'1589328000000'; // timestamp let Ad = new Date(ds); let Bd = Date.parse(ds); let Cd = moment(ds); let Dd = moment(ds).toDate(); let Ed = parseDate(ds); let At = new Date(ts); let Ct = moment(ts); let Dt = moment(ts).toDate(); log = (n,d) => console.log(`${n}: ${+d} ${d}`); console.log('from date string:', ds) log('Ad', Ad); log('Bd', Bd); log('Cd', Cd); log('Dd', Dd); log('Ed', Ed); console.log('from timestamp:', ts) log('At', At); log('Ct', Ct); log('Dt', Dt); function parseDate(dateStr) { let [year,month,day] = dateStr.split(' ')[0].split('-'); let d=new Date(0); d.setUTCFullYear(year); d.setUTCMonth(month-1); d.setUTCDate(day) return d; } <script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.19.1/moment-with-locales.min.js"></script> This snippet only presents used soultions
铬检测结果
将其作为参数传递给Date():
var st = "date in some format"
var dt = new Date(st);
您可以使用，例如:dt.getMonth()来访问日期、月、年。
推荐文章
- HtmlSpecialChars在JavaScript中等价于什么?
- React: 'Redirect'没有从' React -router-dom'中导出
- 如何在React中使用钩子强制组件重新渲染?
- 我如何使用Jest模拟JavaScript的“窗口”对象?
- 我如何等待一个承诺完成之前返回一个函数的变量?
- 在JavaScript中根据键值查找和删除数组中的对象
- 使嵌套JavaScript对象平放/不平放的最快方法
- 如何以及为什么'a'['toUpperCase']()在JavaScript工作?
- 有Grunt生成index.html不同的设置
- 文档之间的区别。addEventListener和window。addEventListener?
- 如何检查动态附加的事件监听器是否存在?
- 前一个月的Python日期
- 如何写setTimeout与参数Coffeescript
- 将JavaScript字符串中的多个空格替换为单个空格
- JavaScript: override alert()
