如何从时间戳中获取日期？

Question

I have 2 timestamps with different format:

1/2/2021 21:15
19-3-2021 21:15

Is there a method in javascript to get just the date for these timestamps?

Expected output:

'1/2/2021'
'19/3/2021'

I know using substr() is not effective as the length of the date string can vary.

Answer 1

Assuming the two timestamp formats are the only ones to which you need to cater, we can try:

 function getDate(input) { return input.replace(/\s+\d{1,2}:\d{1,2}$/, "").replace(/-/g, "/"); } console.log(getDate("1/2/2021 21:15")); console.log(getDate("19-3-2021 21:15"));

The first regex replacement strips off the trailing time component, and the second replacement replaces dash with forward slash.

Answer 2

1. Use split() to convert string into array based on space.

2. Then use replaceAll() on each element of the array, which will replace all the dash(-) which are in dates to slash (/)

3. Use includes() to check if slash(/) is present or not, as it will separate data(d/m/y) with time(h:m)

 function getDateFun(timestamp) { let timeStr = timestamp; let splitStamp = timeStr.split(" "); let dates = []; for (let i = 0; i < splitStamp.length; i++) { if (splitStamp[i].includes("/") || splitStamp[i].includes("-")) dates.push(splitStamp[i]); } console.log(dates.toString()); } getDateFun("1/2/2021 21:15"); getDateFun("19-3-2021 21:15"); getDateFun("1/2/2021 21:15 19-3-2021 21:15");

Update

Based on RobG comment, the same can be achieved by using Regular Expressions and replace() method.

 function getDateFun(timestamp){ return timestamp.split(' ')[0].replace(/\D/g, '/'); } console.log(getDateFun("28/03/2021 07:50")); console.log(getDateFun("19-02-2021 15:30"));

 function getDateFun(timestamp){ return timestamp.replace(/(\d+)\D(\d+)\D(\d+).*/,'$1/$2/$3') } console.log(getDateFun("28/03/2021 07:50")); console.log(getDateFun("19-02-2021 15:30"));

Answer 3

Assuming that your dates have a space character between the date and time you can use the split() method:

 let firstDate = '1/2/2021 21:15'; let secondDate = '19-3-2021 21:15'; // [0] is the first element of the splitted string console.log(firstDate.split(" ")[0]); console.log(secondDate.split(" ")[0]);

Or you can then also use substr() by first finding the position of the space character:

 let firstDate = '1/2/2021 21:15'; let secondDate = '19-3-2021 21:15'; let index1 = firstDate.indexOf(' '); let index2 = secondDate.indexOf(' '); console.log(firstDate.substr(0, index1)); console.log(secondDate.substr(0, index2));