Sort javascript array with respect to an attribute

Question

I am new to JSON and Javasript.

I have data in JSON

var data = [
"FirstName: 'xyz', Lastname 'QSD', rollNo:'1',EntryDate:'2012-09-11T17:35:31.835+02:00'"

"FirstName: 'abc', Lastname 'qgr', rollNo:'2',EntryDate:'2012-08-11T17:35:31.835+02:00'"

]

I want to sort it according to FirstName ,or by roll no or any other attribute i choose.

Thanks in advance.

Answer 1

Since you tagged the question as dojo , here is the dojo way via dojo/store/Memory . There is also a tutorial to Dojo Object Store .

See the code below in action at jsFiddle: http://jsfiddle.net/phusick/MGUBT/

require(["dojo/store/Memory"], function(Memory) {

    var data = [
        { FirstName: 'xyz', Lastname: 'QSD', rollNo: '1', EntryDate: '2012-09-11T17:35:31.835+02:00' },
        { FirstName: 'abc', Lastname: 'qgr', rollNo: '2', EntryDate: '2012-08-11T17:35:31.835+02:00' }
    ];

    var store = new Memory({ data: data });

    var sortedData = store.query(null, {
        sort:[{ attribute: "FirstName", descending: false }]
    });

    console.dir(sortedData);

});
​

Answer 2

If data is supposed to be an array containing objects, you could do:

data.sort(function(a,b) {
    return a.FirstName > b.FirstName;
})

Answer 3

The first problem is the structure of your data. You have effectively an array like

var data = [ "foo", "bar" ];

and these lines of strings contain serialized data. So first we need to extract the data via any method given in this SO question , for example the JSON library method:

var interpreted = [];
for(var i=0; i<data.length; ++i) {
    interpreted[i] = JSON.parse(data[i]);
}

Now we have structures like this:

[
    0: {
        'Firstname': 'xyz',
        'Lastname' : 'QSD', // there is a colon missing in the
                            // source, I'm guessing accidentally
        ...
    },
    1: {
        'Firstname' : 'abc',
        ...
    }
]

So we can access the firstname via interpreted[i].Firstname . Now we can sort in a similar way to this other SO question , by passing sort() a comparison function :

interpreted.sort(function(a,b) { 
    if(a.Firstname == b.Firstname)
        return 0;
    if(a.Firstname > b.Firstname)
        return 1;
    else
        return -1
} );

Where you need to swap 1 and -1 if you want to sort descending.

Answer 4

Your first problem is that the members are string literals, not objects. But as long as they are written as they are now, you can just use a simple sort . Just write

data.sort();

and the array will be sorted by first name.

What you want is something like:

var data = [
 {FirstName: 'xyz', Lastname 'QSD', rollNo:'1',EntryDate:'2012-09-11T17:35:31.835+02:00'},
 {FirstName: 'abc', Lastname 'qgr', rollNo:'2',EntryDate:'2012-08-11T17:35:31.835+02:00'}
]

You can then sort using the sort() function providing your own comparator like this:

data.sort(function (a, b) {
    return // return a positive number if a > b
           // use a.FirstName to access value of FirstName in a. 

})