How to sort a JavaScript array of objects by nested object property?

I have this function to sort a JavaScript array of objects based on a property:

// arr is the array of objects, prop is the property to sort by
var sort = function (prop, arr) {
    arr.sort(function (a, b) {
        if (a[prop] < b[prop]) {
            return -1;
        } else if (a[prop] > b[prop]) {
            return 1;
        } else {
            return 0;
        }
    });
};

It works with arrays like this:

sort('property', [
    {property:'1'},
    {property:'3'},
    {property:'2'},
    {property:'4'},
]);

But I want to be able to sort also by nested properties, for example something like:

sort('nestedobj.property', [
    {nestedobj:{property:'1'}},
    {nestedobj:{property:'3'}},
    {nestedobj:{property:'2'}},
    {nestedobj:{property:'4'}}
]);

However this doesn't work because it is not possible to do something like object['nestedobj.property'], it should be object['nestedobj']['property'].

Do you know how could I solve this problem and make my function work with properties of nested objects?

Thanks in advance

Solution 1:

You can split the prop on ., and iterate over the Array updating the a and b with the next nested property during each iteration.

Example: http://jsfiddle.net/x8KD6/1/

var sort = function (prop, arr) {
    prop = prop.split('.');
    var len = prop.length;

    arr.sort(function (a, b) {
        var i = 0;
        while( i < len ) { a = a[prop[i]]; b = b[prop[i]]; i++; }
        if (a < b) {
            return -1;
        } else if (a > b) {
            return 1;
        } else {
            return 0;
        }
    });
    return arr;
};

Solution 2:

Instead of passing the property as a string, pass a function that can retrieve the property from the top level object.

var sort = function (propertyRetriever, arr) {
    arr.sort(function (a, b) {
        var valueA = propertyRetriever(a);
        var valueB = propertyRetriever(b);

        if (valueA < valueB) {
            return -1;
        } else if (valueA > valueB) {
            return 1;
        } else {
            return 0;
        }
    });
};

Invoke as,

var simplePropertyRetriever = function(obj) {
    return obj.property;
};

sort(simplePropertyRetriever, { .. });

Or using a nested object,

var nestedPropertyRetriever = function(obj) {
    return obj.nestedObj.property;
};

sort(nestedPropertyRetriever, { .. });