Convert dd-mm-yyyy string to date_问答_开发者_运维开发者技术经验分享

i am trying to convert a string in the format dd-mm-yyyy into a date object in JavaScript using the following:

 var from = $("#datepicker").val();
 var to = $("#datepickertwo").val();
 var f = new Date(from);
 var开发者_如何学Go t = new Date(to);

("#datepicker").val() contains a date in the format dd-mm-yyyy. When I do the following, I get "Invalid Date":

alert(f);

Is this because of the '-' symbol? How can I overcome this?

Split on "-"

Parse the string into the parts you need:

var from = $("#datepicker").val().split("-")
var f = new Date(from[2], from[1] - 1, from[0])

Use regex

var date = new Date("15-05-2018".replace( /(\d{2})-(\d{2})-(\d{4})/, "$2/$1/$3"))

Why not use regex?

Because you know you'll be working on a string made up of three parts, separated by hyphens.

However, if you were looking for that same string within another string, regex would be the way to go.

Reuse

Because you're doing this more than once in your sample code, and maybe elsewhere in your code base, wrap it up in a function:

function toDate(dateStr) {
  var parts = dateStr.split("-")
  return new Date(parts[2], parts[1] - 1, parts[0])
}

Using as:

var from = $("#datepicker").val()
var to = $("#datepickertwo").val()
var f = toDate(from)
var t = toDate(to)

Or if you don't mind jQuery in your function:

function toDate(selector) {
  var from = $(selector).val().split("-")
  return new Date(from[2], from[1] - 1, from[0])
}

Using as:

var f = toDate("#datepicker")
var t = toDate("#datepickertwo")

Modern JavaScript

If you're able to use more modern JS, array destructuring is a nice touch also:

const toDate = (dateStr) => {
  const [day, month, year] = dateStr.split("-")
  return new Date(year, month - 1, day)
}

regular expression example:

new Date( "13-01-2011".replace( /(\d{2})-(\d{2})-(\d{4})/, "$2/$1/$3") );

Another possibility:

var from = "10-11-2011"; 
var numbers = from.match(/\d+/g); 
var date = new Date(numbers[2], numbers[0]-1, numbers[1]);

Match the digits and reorder them

Using moment.js example:

var from = '11-04-2017' // OR $("#datepicker").val();
var milliseconds = moment(from, "DD-MM-YYYY").format('x');
var f = new Date(milliseconds)

Use this format: myDate = new Date('2011-01-03'); // Mon Jan 03 2011 00:00:00

var from = $("#datepicker").val(); 
var f = $.datepicker.parseDate("d-m-Y", from);

You can also write a date inside the parentheses of the Date() object, like these:

new Date("Month dd, yyyy hh:mm:ss")
new Date("Month dd, yyyy")
new Date(yyyy,mm,dd,hh,mm,ss)
new Date(yyyy,mm,dd)
new Date(milliseconds)

In my case

new Date("20151102034013".replace(/(\d{4})(\d{2})(\d{2})(\d{2})(\d{2})(\d{2})/, "$1-$2-$3T$4:$5:$6"))

Result: Mon Nov 02 2015 04:40:13 GMT+0100 (CET) then I use .getTime() to work with milliseconds

The accepted answer kinda has a bug

var from = $("#datepicker").val().split("-")
var f = new Date(from[2], from[1] - 1, from[0])

Consider if the datepicker contains "77-78-7980" which is obviously not a valid date. This would result in:

var f = new Date(7980, 77, 77);
=> Date 7986-08-15T22:00:00.000Z

Which is probably not the desired result.

The reason for this is explained on the MDN site:

Where Date is called as a constructor with more than one argument, if values are greater than their logical range (e.g. 13 is provided as the month value or 70 for the minute value), the adjacent value will be adjusted. E.g. new Date(2013, 13, 1) is equivalent to new Date(2014, 1, 1).

A better way to solve the problem is:

const stringToDate = function(dateString) {
  const [dd, mm, yyyy] = dateString.split("-");
  return new Date(`${yyyy}-${mm}-${dd}`);
};

console.log(stringToDate('04-04-2019'));
// Date 2019-04-04T00:00:00.000Z

console.log(stringToDate('77-78-7980'));
// Invalid Date

This gives you the possibility to handle invalid input.

For example:

const date = stringToDate("77-78-7980");

if (date === "Invalid Date" || isNaN(date)) {
  console.log("It's all gone bad");
} else {
  // Do something with your valid date here
}

You can use an external library to help you out.

http://www.mattkruse.com/javascript/date/source.html

getDateFromFormat(val,format);

Also see this: Parse DateTime string in JavaScript

You can just:

var f = new Date(from.split('-').reverse().join('/'));

let dateString  = '13-02-2021' //date string in dd-mm-yyyy format

let dateArray = dateString.split("-");
//dateArray[2] equals to 2021
//dateArray[1] equals to 02
//dateArray[0] equals to 13

// using template literals below

let dateObj = new Date(`${dateArray[2]}-${dateArray[1]}-${dateArray[0]}`);

// dateObj equals to Sat Feb 13 2021 05:30:00 GMT+0530 (India Standard Time)

//I'm from India so its showing GMT+0530

P.S : Always refer docs for basics, MDN or DevDocs

Take a look at Datejs for all those petty date related issues.. You could solve this by parseDate function too

You could use a Regexp.

var result = /^(\d{2})-(\d{2})-(\d{4})$/.exec($("#datepicker").val());
if (result) {
    from = new Date(
        parseInt(result[3], 10), 
        parseInt(result[2], 10) - 1, 
        parseInt(result[1], 10)
    );
}