Возвращает все комбинации чисел из массива, дающие в сумме 10.

gistfile1.js

// Все комбинации чисел из массива, дающие в сумме 10
// getCombinations([2,4,6,5,1]) // -> 4,6 и 4,5,1

function getCombinations(array){

    var allCombinations = [];

    function getLevelCombinations(arr, indexes){

        console.log('combinations > ', stringifyCombinations(allCombinations).split('\n'));

        indexes = indexes || [];

        var currentCombinations = [];
        var objects = indexes.map(function(obj){
            return {
                index: obj.index,
                number: arr[obj.index]
            };
        });

        function indexOf(list, index){
            for ( var i = 0, l = list.length; i < l; i++ ) {
                if ( list[i].index === index ) {
                    return true;
                }
            }
            return false;
        };

        console.log('objects:', JSON.stringify(objects));

        arr.forEach(function(el, i){
            if ( !indexOf(indexes, i) ) {
                var newCombination = objects.slice();
                newCombination.push({
                    index: i,
                    number: el
                });
                currentCombinations.push(newCombination);
            }
        });

        console.log('Combinations:\n', stringifyCombinations(currentCombinations));

        currentCombinations.forEach(function(combination){
            getLevelCombinations(arr, combination);
        });

        allCombinations = allCombinations.concat(currentCombinations);
    }

    function stringifyCombinations(combinations){
        return combinations.map(function(combination){
            return combination.map(function(el){
                return el.number;
            }).join('-');
        }).join('\n');
    };

    function filterDuplicates(combinations){

        var filtered = [];

        function inArray(combination, combinations){
            for ( var i = 0, l = combinations.length; i < l; i++ ) {
                var current = combinations[i];
                if ( areArraysEqual( getIndexes(current), getIndexes(combination) ) ) {
                    console.log(
                        'Removed duplicate:',
                        stringifyCombinations([combination]), ' == ',
                        stringifyCombinations([current])
                    );
                    return true;
                }
            }
            return false;
        };

        function areArraysEqual(arr1, arr2){
            return arr1.toString() === arr2.toString();
        };

        function getIndexes(combination){
            return combination.map(function(el){
                return el.index;
            }).sort();
        };

        //console.log('zzz', combination)

        combinations.forEach(function(combination){
            if ( !inArray(combination, filtered) ) {
                filtered.push(combination);
            }
        });

        return filtered;
    };

    function getSumm(arr){
        return arr.reduce(function(prev, current){
            return prev + current;
        });
    };

    function filterByLength(combinations){
        return combinations.filter(function(combination){
            return combination.length > 1;
        });
    };

    function filterBySumm(combinations){
        return combinations.filter(function(combination){
            var numbers = combination.map(function(el){
                return el.number;
            });
            return getSumm(numbers) === 10;
        });
    };

    getLevelCombinations(array); // TODO: refactor

    return '\n\nКомбинации:\n' + stringifyCombinations(
        filterBySumm(
            filterDuplicates(
                filterByLength(allCombinations)
            )
        )
    )

};