Sorter

function sortBy(sequence, sorters) {
    return sequence.slice().sort(function (a, b) {
        var comparison = 0;
        for (var i = 0; i < sorters.length; ++i) {
            comparison = sorters[i](a, b);
            if (comparison !== 0) {
                return comparison;
            }
        }
        return comparison;
    });
}

Tests

it('should sort by using the comparator given', function () {
    // Given
    var list = [7, 4, 5];
    var comparator = function(a, b) {
        return a - b;
    };
    
    // When
    var sortedList = sortBy(list, [comparator]);
    
    // Then           
    expect(sortedList[0]).toBe(4);
    expect(sortedList[1]).toBe(5);
    expect(sortedList[2]).toBe(7);
 
});
 
it('should not modify the original', function () {
    // Given
    var list = [7, 4, 5];
    var comparator = function (a, b) {
        return a - b;
    };
 
    // When
    var sortedList = sortBy(list, [comparator]);
 
    // Then           
    expect(list[0]).toBe(7);
    expect(list[1]).toBe(4);
    expect(list[2]).toBe(5);
 
});
 
it('should use subsequent comparators if the result of the current one is a tie', function () {
    // Given
    var list = [{ a: 1, b: 2 }, { a: 1, b: 1 }, { a: 1, b: 0 }];
 
    // Asc
    var comparator1 = function (a, b) {
        return a.a - b.a;
    };
    // Desc
    var comparator2 = function (a, b) {
        return b.b - a.b;
    };
 
    // When
    var sortedList = sortBy(list, [comparator1, comparator2]);
 
    // Then           
    expect(list[0].b).toBe(2);
    expect(list[1].b).toBe(1);
    expect(list[2].b).toBe(0);
 
});