Javascript custom sorting an array of objects by year with 'pre year'

Question

So I have an array of objects ex:

var a = {user: [
 {year:'1950',name:'Joe'},
 {year:'19XX',name:'Chris'},
 {year:'1980',name:'Bob'},
 {year:'1955',name:'Jan'}
]}

I use this data to template out simple elements holding the year and name. I also have option via a select element to sort this data and then use the sorted to template it out again in order of sort. (bob,chris,jan,joe) or year. But my issue starts with year.

I am needing to continue to use a simple plugin jsonQ (http://ignitersworld.com/lab/jsonQ.html) to edit and sort data, and need to have data for year actually be a little different than desc or asc.

1st I need to edit data at various parts, like year (19XX should become 'Pre 1950'):

//inside ajax success function
var dataObj = jsonQ(data);

dataObj.find('year').value(function (data){
   if (data == '19XX') {
       return 'pre 1953'
   } else {
       return data;
   }
});

Now I will have a final product data set that needs to be sorted.

var orderedData = dataObj.sort('year', {'order' : 'ASC'});

But this gives me the data back as:

{
 user: [
  {year:'1950',name:'Joe'},
  {year:'1955',name:'Jan'},     
  {year:'1980',name:'Bob'},
  {year:'Pre 1950',name:'Chris'}
 ]
}

What I need is the data to be returned as:

{
 user: [
  {year:'Pre 1950',name:'Chris'},
  {year:'1950',name:'Joe'},
  {year:'1955',name:'Jan'},     
  {year:'1980',name:'Bob'}
 ]
}

Any suggestions?

You need to define your own compairing function. Actually P is lexicographically bigger than any digit. — Luis Sieira
– Luis Sieira, Commented Jan 6, 2017 at 19:18

salezica · Accepted Answer · 2017-01-06 19:54:19Z

2

Well, you can implement your own sorting criterion, and pass it to Array.sort().

This criterion takes the form of a function(a, b) that returns a number:

Negative if a should go before b in the sorted list
Zero if a and b are essentially equal
Postive if a should go after b

This may look pretty arbitrary, but think about it this way: in the simple case of sorting numbers from lesser to greater, the function returns a - b. So, f(a, b) is a - b, and a - b < 0 means a < b.

Back to your case. Let's implement a criterion function that sorts the years from lesser to greater, putting Pre 1950 at the top:

function byYear(a, b) {
  if (a === "Pre 1950") return -1 // a goes before
  if (b === "Pre 1950") return 1  // b goes before

  return parseInt(a) - parseInt(b) // lesser goes before
})

Try it in the browser console:

> ["1980", "1970", "Pre 1950"].sort(byYear)
["Pre 1950", "1970", "1980"]

Given that you're sorting objects, you'll need to adapt the criterion function above to work with a.year and b.year.

edited Jan 6, 2017 at 19:54

answered Jan 6, 2017 at 19:21

salezica

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3 Comments

Mihailo Over a year ago

The if (a === "Pre 1950") return -1; part is not necessary.

Mihailo Over a year ago

I guess you have a point. +1 for the detailed answer. Great job.

lscmaro Over a year ago

@slezica - Yea, +1 this is a great answer for understanding this kind of manipulation .. I was stuck with this plugin specifically.

Nina Scholz · Accepted Answer · 2017-01-06 19:28:57Z

0

You could sort the array in three steps

sort priority years, like 19XX
sort by years without priority
sort by name.

var a = { user: [{ year: '1950', name: 'Joe' }, { year: '19XX', name: 'Chris' }, { year: '1980', name: 'Bob' }, { year: '1955', name: 'Jan' }] };

a.user.sort(function (a, b) {
    var order = { '19XX': -1 };
    return (order[a.year] || 0) - (order[b.year] || 0) || a.year - b.year || a.name.localeCompare(b.name);
});

console.log(a);

edited Jan 6, 2017 at 19:28

answered Jan 6, 2017 at 19:22

Nina Scholz

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Comments

lscmaro · Accepted Answer · 2017-01-06 20:03:58Z

0

I have just found the solution, shortly after posting, while using the plugin. (which is what I wanted, Sorry, I should have specified that more).

My problem was in my options passed into the plugin's sort()method. not easy to find since documentation isn't 100.

var orderedData = dataObj.sort('year', {
  'order' : 'ASC',
  logic: function(val){
     return (val == 'pre 1950') ? '1911' : val;
  }
});

What this is essentially doing is replacing 'pre 1950' with 1911, just for sorting purposes.

edited Jan 6, 2017 at 20:03

answered Jan 6, 2017 at 19:57

lscmaro

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2 Comments

Nina Scholz Over a year ago

you could skip paranteses around the condition.

lscmaro Over a year ago

@NinaScholz - you are right .. old habits die hard :)

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