const find = (target, data, resultMas = [], sum = 0) => {
 	// случай если сумма чисел меньше target
	if (!data.length) {
    	    console.error('max value:!', sum);
            return
        }
	const maxNum = Math.max.apply(Math, data);
        const index = data.indexOf(maxNum);
    
        resultMas.push(maxNum);
        sum = resultMas.reduce((prev, next) => prev + next);
    
        const test = sum > target;
        if (test) {
    	    return resultMas
        } else {
            data.splice(index, 1);
            return find(target, data, resultMas, sum);
        }
};

<script>
function fn(a, b) {
    a = a.slice(0).sort(function(a, b) {
        return b - a
    }).filter(function(a) {
        var c = 0 < b;
        b -= a;
        return 0 < c
    });
    return 0 < b ? !1 : a
};
document.write(JSON.stringify(fn([2, 5, 9, 11, 1, 2, 4],12)));

</script>

var arr = [2, 5, 9, 11, 1, 2, 4], x = 12;
arr.sort((a, b)=> b-a).reduce((sum, el, i) => { 
	if (sum > x) arr.length = i;
	if (sum < x && i==arr.length-1) arr = false; // если все же X больше
	return sum + el;
});
alert(arr);

<script>
function fn(a, c) {
    a = a.slice(0).sort(function(a, b) {
        return b - a
    });
    for (var b = 0; b < a.length; b++) {
        if (c < a[b]) return a.slice(0, ++b);
        c -= a[b]
    }
    return !1
};
document.write(JSON.stringify(fn([2, 5, 9, 11, 1, 2, 4],12)));

</script>

var arr = [2, 5, 9, 11, 1, 2, 4], x = 12, sum = 0;
arr.length = arr.sort((a, b)=> b-a).findIndex((el) => (sum += el) > x )+1;
if(!arr.length) arr = false;
alert(arr);