将字符串转换为日期

Question

I have the following script which joins 2 feeds and displays them on the screen

$.when( //get feed 1, //get feed 2 ).done(function(a1, a2){

    var data = a1[0]response.Data.feed.entries.concat(a2[0].responseData.feed.entries);

    var sorted = data.sort(function(a, b) {
        if(a.publishedDate > b.publishedDate) {
            return 1
        }
        if(a.publishedDate < b.publishedDate) {
            return -1
        }
        return 0
    });

    for( i = o; i <= sorted.length - 1; i++ ) {
        document.write(sorted[i].title);
        document.write(sorted[i].publishedDate);
    }

});

This returns all the rows, but it doesn't sort the rows. The sorting seems completely random. I'm assuming it's because the dates are formatted as follows in the JSON data:

Mon, 23 Sep 2013 04:37:45 -0700

1. What does that -0700 mean
2. How do I convert that date string into a proper date object so I can sort the results correctly?

Answer 1

1. -0700 means the UTC offset UTC-07:00 .
2. I'm strongly recommend you to use Moment.js library to deal with date and time, formatting and conversions to make your "Date & Time JavaScript Life" easy and funny.

As Alnitak said this particular format is accepted by Date.parse therefore if you use one of accepted formats you can just use native JavaScript for sorting.

var dateStrings,
    sortDates;

dateStrings = [
    'Mon, 23 Sep 2013 04:37:45 -0700',
    'Sun, 22 Sep 2013 05:27:32 +0300',
    'Mon, 23 Sep 2013 03:14:17 -0700'
];

sortDates = function(dateStrings) {
    return dateStrings.sort(function(a, b) {
        return new Date(a) - new Date(b);
    });
};

console.log(sortDates(dateStrings));

Fiddle

The variable sorted in your code snippet could be properly retrieved in this way:

var sorted = data.sort(function(a, b) {
    return new Date(a.publishedDate) - new Date(b.publishedDate);
});

Answer 2

You can pass the string to new Date(...) to convert to a real Date object.

To sort however you also need to pass a specific sort function because default Javascript sort on arrays just converts elements to string and compares the result of conversion (thus any "Mon" day will happen to be placed before any "Sun" day).

Something that should work is

dates.sort(function(a, b){ return a - b; });

Answer 3

Well, -0700 means.. is 7 hours earlier than Greenwich Mean ...yor can check more in wikipedia

And if you want to convert any date properly, i strongly recommend you to use the library DateJS ( http://www.datejs.com/ )

You can use syntatic sugarr..!! to create your object...

Date.parse('Thu, 1 July 2013 20:20:20');

voila.. its very easy...