A JavaScript map implementation. Will be on my blog soon: http://oli.me.uk/

map.js

/**
 * A simple map implementation. Uses two arrays to store the keys and values as well as indexOf to search through them.
 *
 * You could swap indexOf for a binary search if you need more speed: http://oli.me.uk/2013/06/08/searching-javascript-arrays-with-a-binary-search/
 *
 * @class
 */
function Map() {
	this._createStorage();
}

/**
 * Assigns a vale to a key. Will override a value if you use the same key twice.
 *
 * @param {*} key
 * @param {*} value
 * @return {Object} Current map instance to allow chaining.
 */
Map.prototype.set = function (key, value) {
	var index = this._getIndexOf(key);
	this._keys[index] = key;
	this._values[index] = value;
	return this;
};

/**
 * Fetch a value which has already been assigned to the specified key.
 *
 * @param {*} key
 * @return {*} The value that was assigned to the key, if any.
 */
Map.prototype.get = function (key) {
	var index = this._getIndexOf(key);
	return this._values[index];
};

/**
 * Removes the value from the map that was assigned to the provided key.
 *
 * @param {*} key
 * @return {Object} Current map instance to allow chaining.
 */
Map.prototype.remove = function (key) {
	var index = this._getIndexOf(key);

	if (index !== this._keys.length) {
		this._keys.splice(index, 1);
		this._values.splice(index, 1);
	}

	return this;
};

/**
 * Wipes the whole map objects storage. The same as calling `remove` on each value, one by one.
 *
 * @return {Object} Current map instance to allow chaining.
 */
Map.prototype.clear = function () {
	this._createStorage();
	return this;
};

/**
 * Creates the storage arrays to be used internally.
 *
 * @return {Object} Current map instance to allow chaining.
 * @private
 */
Map.prototype._createStorage = function () {
	this._keys = [];
	this._values = [];
};

/**
 * Fetches the index of the provided key. If a matching key can't be found, it returns where you should inject that value within the storage array.
 *
 * @param {*} key
 * @return {Object} Current map instance to allow chaining.
 * @private
 */
Map.prototype._getIndexOf = function (key) {
	var index = this._keys.indexOf(key);
	return index === -1 ? this._keys.length : index;
};