How to sort array based on date in descending order if value exists in JS?

Question

I am trying to sort data based on descending order of publishDate but it's not working. In some array, publishDate is coming and in some array, it's not coming.

[
    {
        "id": "brexit-delay",
        "title": "Brexit Delay",
        "publish": {

            "publishDate": "2019-8-30T12:25:47.938Z",
        }
    },   

    {
        "id": "brexit-delay",
        "title": "Example 3"
    },    

    {
        "id": "brexit-delay",
        "title": "Example 2",
        "publish": {           
            "publishDate": "2019-6-30T12:25:47.938Z",
        }
    },

    {
        "id": "brexit-delay",
        "title": "Example 5"
    },    

    {
        "id": "brexit-delay",
        "title": "Example 5",
        "publish": {           
            "publishDate": "2019-10-25T12:25:47.938Z",
        }
    }
]

Js code:

data.sort(function(a, b){
    if("publish" in a && "publish" in b){
        return new Date(a.publish.publishDate) - new Date(b.publish.publishDate)
    }
} );

And how would you like to treat those objects where the publishDate is missing? Are they later that everything or sooner? — Sebastian Kaczmarek
– Sebastian Kaczmarek, Commented Dec 20, 2019 at 7:37
Additionally, you are checking 'publish' in a while the key is called publishDate in the original object, so I guess it should be 'publishDate' in a — Sebastian Kaczmarek
– Sebastian Kaczmarek, Commented Dec 20, 2019 at 7:39
@SebastianKaczmarek publishDate is a key of publish, so it doesn't matter. I'm assuming that if publish key exist then publish.publishDate will also have some date value. — Gulam Hussain
– Gulam Hussain, Commented Dec 20, 2019 at 7:40
@SebastianKaczmarek i want object without publishDate treat as sooner — Addy
– Addy, Commented Dec 20, 2019 at 7:42
@hussain.codes ah, sorry, you are right. I didn't see the publish key ;) — Sebastian Kaczmarek
– Sebastian Kaczmarek, Commented Dec 20, 2019 at 7:44

StepUp · Accepted Answer · 2019-12-20 09:59:33Z

3

Check whether the property exists and based on this return order:

const myParseDate = date_string => {
    let [y,M,d,h,m,s] = date_string.split(/[- :T]/);
    return new Date(y,parseInt(M)-1,d,h,parseInt(m),s.replace('Z',''));
}

arr.sort(function(a, b){
    if (a.publish  && b.publish) {
        return myParseDate(b.publish.publishDate) - myParseDate(a.publish.publishDate)
    }
    else if (a.hasOwnProperty("publish"))
        return -1;
    else if (b.hasOwnProperty("publish"))
        return 1;
    else
        return 0;
} );

An example:

const arr = [
{
    "id": "brexit-delay",
    "title": "Brexit Delay",
    "publish": {
        "publishDate": "2019-8-30T12:25:47.938Z",
    }
},
{
    "id": "brexit-delay",
    "title": "Example 3"
},
{
    "id": "brexit-delay",
    "title": "Example 2",
    "publish": {
        "publishDate": "2019-6-30T12:25:47.938Z",
    }
},
{
    "id": "brexit-delay",
    "title": "Example 5"
},
{
    "id": "brexit-delay",
    "title": "Example 5",
    "publish": {
        "publishDate": "2019-10-25T12:25:47.938Z",
    }
}
]

const myParseDate = date_string => {
let [y,M,d,h,m,s] = date_string.split(/[- :T]/);
return new Date(y,parseInt(M)-1,d,h,parseInt(m),s.replace('Z',''));
}

arr.sort(function(a, b){    
if (a.publish  && b.publish)
    return myParseDate(b.publish.publishDate) - myParseDate(a.publish.publishDate)
else if (a.hasOwnProperty("publish"))
    return -1;
else if (b.hasOwnProperty("publish"))
    return 1;
else
    return 0;
} );

console.log(arr);

UPDATE:

If you want ascending order, then just change place of a and b:

arr.sort(function(a, b){
    if (a.publish  && b.publish)
        return myParseDate(a.publish.publishDate) - myParseDate(b.publish.publishDate)
    else if (a.hasOwnProperty("publish"))
        return -1;
    else if (b.hasOwnProperty("publish"))
        return 1;
    else
        return 0;
} );

An example:

const arr = [
    {
        "id": "brexit-delay",
        "title": "Brexit Delay",
        "publish": {
            "publishDate": "2019-8-30T12:25:47.938Z",
        }
    },
    {
        "id": "brexit-delay",
        "title": "Example 3"
    },
    {
        "id": "brexit-delay",
        "title": "Example 2",
        "publish": {
            "publishDate": "2019-6-30T12:25:47.938Z",
        }
    },
    {
        "id": "brexit-delay",
        "title": "Example 5"
    },
    {
        "id": "brexit-delay",
        "title": "Example 5",
        "publish": {
            "publishDate": "2019-10-25T12:25:47.938Z",
        }
    }
]

const myParseDate = date_string => {
    let [y,M,d,h,m,s] = date_string.split(/[- :T]/);
    return  new Date(y,parseInt(M)-1,d,h,parseInt(m),s.replace('Z',''));
}

arr.sort(function(a, b){
    if (a.publish  && b.publish)
        return myParseDate(a.publish.publishDate) - myParseDate(b.publish.publishDate)
    else if (a.hasOwnProperty("publish"))
        return -1;
    else if (b.hasOwnProperty("publish"))
        return 1;
    else
        return 0;
} );

console.log(arr);

edited Dec 20, 2019 at 9:59

answered Dec 20, 2019 at 7:43

StepUp

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5 Comments

Addy Over a year ago

According to output of your code this Example 2 is coming on 2nd position but it should be on first position.

StepUp Over a year ago

@Addy Example2 has 2019-6-30T12:25:47.938Z, however Brexit Delay is 2019-8-30T12:25:47.938Z and it is descending order

Addy Over a year ago

What changes, i need to made if i want asc order

Addy Over a year ago

your code working fine with js execution. But i am trying to use code in node js i get issue with array which don't have date.

StepUp Over a year ago

@Addy as a good practice at stackoverflow, it is better to have one question per post. Could you create a new post with error?

Luke · Accepted Answer · 2019-12-20 07:43:18Z

0

a sort function must return a number. you have an if statement inside your sort compare function with and comparator, so if some object does not have publish date, the compare function does not return anything, you might try to place more if's

a.sort((a, b) => {
    if (a.publish && b.publish) {
        return //compare condition
    } else if (a.publish && !b.publish) {
        return //compare condition
    } else if (!a.publish && b.publish) {
        return //compare condition
    } else {
        return //compare condition
    }
});

answered Dec 20, 2019 at 7:43

Luke

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Comments

user54987 · Accepted Answer · 2019-12-20 07:44:39Z

0

You need to update your code to this:

data.sort(function(a, b){
    if("publish" in a && "publish" in b){
        return new Date(a.publish.publishDate.replace("T", " ") - new Date(b.publish.publishDate.replace("T", " "))
    }
} );

new Date("2019-10-25T12:25:47.938Z") just returns the string "Invalid Date" unless you replace the "T"

answered Dec 20, 2019 at 7:44

user54987

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