Iterate through and array and return the first number that occurs an odd number of times.

oddness.js

var numbers = [1, 1, 2, 3, 2, 3, 7, 8, 8];

var getOddOccurrence = function(numbers) {
	var collected = [],
			keys,
			oddnum;
	
	numbers.forEach(function(number) {
		if(typeof collected[number] === 'undefined') {
			collected[number] = [];
		}
		collected[number].push(number);
	});

	keys = Object.keys(collected);
	keys.forEach(function(key) {
		if(collected[key].length % 2 !== 0) {
			oddnum = collected[key][0];
		}
	});

	return oddnum;
};

getOddOccurrence(numbers); //should log 7