Creating Objects With A Null Prototype In Node.js

cache.js

// In this version of the cache, we're going to use an internal object with a null
// prototype and then assume that no user-provided cache keys will ever conflict with
// native keys.
function SafeCache() {

	var cache = Object.create( null );

	// Reveal the public API.
	return({
		get: get,
		has: has,
		remove: remove,
		set: set
	});


	// ---
	// PUBLIC METHODS.
	// ---


	function get( key ) {

		return( cache[ key ] );

	}


	function has( key ) {

		return( key in cache );

	}


	function remove( key ) {

		return( delete( cache[ key ] ), this );

	}


	function set( key, value ) {

		return( cache[ key ] = value, this );

	}

}


var safeCache = new SafeCache()
	.set( "foo", "Bar" )
	.set( "hello", "world" )
	.set( "beep", "boop" )
;

console.log( "## Safe Cache ##" );
console.log( safeCache.has( "foo" ) );
console.log( safeCache.has( "meep" ) );
console.log( safeCache.has( "valueOf" ) );
console.log( safeCache.has( "__proto__" ) );


// ---------------------------------------------------------- //
// ---------------------------------------------------------- //


// In this version of the cache, we're going to use a vanilla object and then take
// special precautions when checking for the existence of or returning a user-provided
// value.
function SaferCache() {

	var cache = {};

	// Reveal the public API.
	return({
		get: get,
		has: has,
		remove: remove,
		set: set
	});


	// ---
	// PUBLIC METHODS.
	// ---


	function get( key ) {

		if ( has( key ) ) {

			return( cache[ key ] );

		}

	}


	function has( key ) {

		return( cache.hasOwnProperty( key ) );

	}


	function remove( key ) {

		return( delete( cache[ key ] ), this );

	}


	function set( key, value ) {

		return( cache[ key ] = value, this );

	}

}


var saferCache = new SaferCache()
	.set( "foo", "Bar" )
	.set( "hello", "world" )
	.set( "beep", "boop" )
;

console.log( "## Safer Cache ##" );
console.log( saferCache.has( "foo" ) );
console.log( saferCache.has( "meep" ) );
console.log( saferCache.has( "valueOf" ) );
console.log( saferCache.has( "__proto__" ) );

null-prototype.js

// Create an object that has no prototype. This will prevent any default keys from
// existing in the object. This means that ANY and ALL keys in this object must be
// user-provided, which makes it very useful for a cache container.
var safeCache = Object.create( null );

// Let's check to see if any common Object keys exist in this object.
[ "hasOwnProperty", "toString", "valueOf", "constructor", "__proto__" ]
	.forEach(
		function iterator( key, index ) {

			console.log( "[ %s ] exists: %s", key, ( key in safeCache ) );

		}
	)
;