insert object into array based on dates oldest to newest

Question

I an array of objects. Each object has a date property and a string property. I also have an empty array. I cant figure out the logic to push the string based on date oldest to newest .

     const oldToNew = []
     for (const baseId in results[key][test]) {
            // log the array of objects
            //example [{string: 'test', date: '2019-03-04T10:36:37.206000Z'}, {string: 'test1', date: '2019-03-010T10:36:37.206000Z'}]
            console.log(results[key][test][baseId])
            results[key][test][baseId].forEach(element => {

            });
        }
     // I want the value to be [test, test1]

So is it that you want an array[string] of sorted items by date (oldest to newest)? — Francis Leigh
– Francis Leigh, Commented Mar 25, 2019 at 14:56

606ep · Accepted Answer · 2019-03-25 15:09:43Z

1

You need to sort initial array with sort and then extract strings with map

something like this:

array.sort((a, b) => a.date < b.date).map(el => el.string);

answered Mar 25, 2019 at 15:09

606ep

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Francis Leigh · Accepted Answer · 2019-03-25 15:22:17Z

1

Use Array.sort to compare the date property of each Object against the one before it - then use Array.map to return an Array of all the items 'string properties.

Update no need to parse the date timestamp.

const items = [{string: 'test4', date: '2019-03-04T10:36:37.206000Z'}, {string: 'test1', date: '2019-03-10T10:36:37.206000Z'}, {string: 'test2', date: '2019-03-09T10:36:37.206000Z'}, {string: 'test3', date: '2019-03-07T10:36:37.206000Z'}]

const strings = items
  .sort((a, b) => b.date > a.date)
  .map(({ string }) => string)

console.log(strings)

edited Mar 25, 2019 at 15:22

answered Mar 25, 2019 at 15:09

Francis Leigh

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4 Comments

Karam Over a year ago

can we do something where there are more than 2 objects in the array

Francis Leigh Over a year ago

@Karam yes, do you have any stub data? this solution should work for any amount.

Francis Leigh Over a year ago

@Karam i have added two other items into the Array. if you have some data you would like to use, update your question with it :-)

iacobalin Over a year ago

you do not need to create new Date. ISO8601 is designed for lexicographical sort. so '2007-01-17T08:00:00Z' < '2008-01-17T08:00:00Z' === true

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