Customizing the sort functionality of JavaScript arrays

Question

I have this very simple sort method:

sortByNumericAttr : function (a, b,attr){            
        a = a[attr];
        b = b[attr];
        return ((a < b) ? -1 : ((a > b) ? 1 : 0));
}

the idea here is that I have different objects with different attr that needs sorting (id,type etc.), so i thought instead of writing different sort function for each (where all the difference is only the sorted attribute), I'd write a generic method and pass the attribute to it.

So if it is written like this i can call it like:

arr.sort(utils.sortByNumericAttr,'typeId');

How can I achieve this or a similar effect, based on this function?

yes, not working, javascript sort only accepts the function, the attr is undefined — Tomer
– Tomer, Commented Feb 13, 2013 at 8:11
Just as an aside 'is this possible' questions generally aren't a useful addition to SO's body of knowledge. Nor are any yes/no questions really. Most of them can even be answered by quickly consulting the relevant documentation (where you can see the correct signature of methods, etc.). Getting help with implementing a feature correctly is an entirely different thing. — nbrooks
– nbrooks, Commented Feb 13, 2013 at 8:16

Blender · Accepted Answer · 2013-02-13 08:11:12Z

8

You can create a function with another function:

function sort_by(attr) {
    return function(o1, o2) {
        var a = o1[attr];
        var b = o2[attr];

        return ((a < b) ? -1 : ((a > b) ? 1 : 0));
    };
}

And then call it like .sort(sort_by('id')).

answered Feb 13, 2013 at 8:11

Blender

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Comments

Nippey · Accepted Answer · 2013-02-13 08:20:06Z

0

If you have a list like this:

var list = [
    {id:5, color:"Green", name:"Audi"},
    {id:1, color:"Red", name:"Ferrari"},
    {id:3, color:"Silver", name:"Mercedes"}
];

You can create sort functions to sort this list for each of the used keys:

function sortById(a,b) { return (a.id-b.id); }
list.sort(sortById);

function sortByName(a,b) { return (a.name.localeCompare(b.name)); }
list.sort(sortByName);

function sortByColor(a,b) { return (a.color.localeCompare(b.color)); }
list.sort(sortByColor);

answered Feb 13, 2013 at 8:20

Nippey

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2 Comments

Tomer Over a year ago

The idea, as i noted in my question, was to write one generic function and not a seperate function for each attribute

Nippey Over a year ago

Ah, right, I see what you mean. And, of course +1 to Blender ;)

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