Loop through json and change format of date

Question

Hello I have some data stored in a variable like so:

var myData = {
    "results": [
        {
            "time": "20040203",
            "count": 2
        },
        {
            "time": "20040205",
            "count": 1
        },
        {
            "time": "20040206",
            "count": 1
        },
        {
            "time": "20040209",
            "count": 2
        },
        {
            "time": "20040210",
            "count": 2
        },
        {
            "time": "20040211",
            "count": 4
        }
    ]
}

The function I am writing needs the date to be in the format that Date.parse() uses for example Tue Jan 01 2013 16:00:00 GMT-0800 (PST)

I also think that the format 2003-01-01 will work also if that is easier.

Is this possible?, if so can anyone shoot me example code or point me in the right direction?

Thanks!

Do you know what time zone the dates should be in? There isn't enough information in the data to know that it should be -0800. — icirellik
– icirellik, Commented Aug 25, 2017 at 18:53
Those "time" values don't resemble JavaScript time values, unless they are all dates from around 1969 or so. Try this in the dev tools JavaScript console for example and see what it prints: new Date(20040211) — Michael Geary
– Michael Geary, Commented Aug 25, 2017 at 18:56

Gavin · Accepted Answer · 2017-08-25 18:57:54Z

3

const myData = {
    "results": [
        {
            "time": "20040203",
            "count": 2
        },
        {
            "time": "20040205",
            "count": 1
        },
        {
            "time": "20040206",
            "count": 1
        },
        {
            "time": "20040209",
            "count": 2
        },
        {
            "time": "20040210",
            "count": 2
        },
        {
            "time": "20040211",
            "count": 4
        }
    ]
};

myData.results.forEach(result => {
  if (parseInt(result.time))
    result.time = new Date(parseInt(result.time)).toString();
});

console.log(myData);

answered Aug 25, 2017 at 18:57

Gavin

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1 Comment

cup_of Over a year ago

hey gavin thanks for your answer, this spits out the data in correct format, but unfortunately the date is wrong. its giving multiple instances of Wed Dec 31 1969 when the real data's year begins at 2004

trincot · Accepted Answer · 2017-08-25 19:01:16Z

You can inject the hyphens to get from a YYYYMMDD to a YYYY-MM-DD format using a replace and a regular expression:

const myData = {
    "results": [
        {
            "time": "20040203",
            "count": 2
        },
        {
            "time": "20040205",
            "count": 1
        },
        {
            "time": "20040206",
            "count": 1
        },
        {
            "time": "20040209",
            "count": 2
        },
        {
            "time": "20040210",
            "count": 2
        },
        {
            "time": "20040211",
            "count": 4
        }
    ]
};

myData.results.forEach(result => {
    result.time = result.time.replace(/(....)(..)(..)/, "$1-$2-$3");
});

console.log(myData);

Ben Fried · Accepted Answer · 2017-08-25 19:04:40Z

2

Your "time" strings are very odd, but I'm assuming "20040203" Is 2004-02-03 or February 3rd, 2004?

You can easily write a function to split those numbers up and format them, or you could use a really nice library like https://momentjs.com/

With moment it would be as simple as:

myData.results.forEach(result => {
  result.time = moment(result.time, 'YYYYMMDD').toDate(); 
  // or use .format('MM-DD-YYYY') or whatever format you like instead of .toDate()
});

answered Aug 25, 2017 at 19:04

Ben Fried

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2 Comments

cup_of Over a year ago

hello thanks for your answer, I prefer not to use an external library, but I will if I cant find another solution

cup_of Over a year ago

I will let you know if i use this library and if it works

Jonathan · Accepted Answer · 2017-08-25 19:20:00Z

1

The following code will parse a string in format "YYYYMMDD" in the corresponding date object. Calling Date#toString() will print it like Tue Feb 03 2004 00:00:00 followed by your timezone.

You may need to take a look at the Date's documentation.

var parseDate = function (str) {
  var year = parseInt(str.substr(0, 4), 10);
  var month = parseInt(str.substr(4, 2), 10) - 1;
  var day = parseInt(str.substr(6, 2), 10);
  return new Date(year, month, day);
}

For example:

var date = parseDate('20040203');
console.log(date.toString());
// prints "Tue Feb 03 2004 00:00:00 GMT+0100 (CET)"

So may use parseDate function in your data set:

myData.results.forEach(result => {
  result.date = parseDate(result.time);
});

edited Aug 25, 2017 at 19:20

answered Aug 25, 2017 at 19:06

Jonathan

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2 Comments

cup_of Over a year ago

hello where are you getting the variable date in result.date from?

cup_of Over a year ago

nevermind, i see what you are doing. you are adding a variable date to each object into the dataset. this works great for me. thanks!

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