or.js

function or(array) {
        var probability = 0
	var combos = []

	for(var i = 1; i < array.length + 1; i++) {
		var combinations = getCombinations(array, i)
		for(var j = 0; j < combinations.length; j++) {
			combos.push(combinations[j])
		}
	}
	for(var i = 0; i < combos.length; i++) {
		product = combos[i][0]
		for(var j = 1; j < combos[i].length; j++) {
			product *= combos[i][j]
		}
		if(combos[i].length % 2 == 0) {
			probability -= product
		} else {
			probability += product
		}
	}
	return probability
}

function getCombinations(array, k) {
	if(k > array.length || k <= 0) {
		return []
	}
	if(k == array.length) {
		return [array]
	}
	if(k == 1) {
		var combinations = []
		for(i = 0; i < array.length; i++) {
			combinations.push([array[i]]);
		}
		return combinations;
	}

	combinations = [];
	for(var i = 0; i < array.length - k + 1; i++) {
		var head = array.slice(i, i + 1);
		var tail = getCombinations(array.slice(i + 1), k - 1);
		for(var j = 0; j < tail.length; j++) {
			combinations.push(head.concat(tail[j]));
		}
	}
	return combinations;
}