function FixedQueue( size, initialValues ){ // If there are no initial arguments, default it to // an empty value so we can call the constructor in // a uniform way. initialValues = (initialValues || []); // Create the fixed queue array value. var queue = Array.apply( null, initialValues ); // Store the fixed size in the queue. queue.fixedSize = size; // Add the class methods to the queue. Some of these have // to override the native Array methods in order to make // sure the queue lenght is maintained. queue.push = FixedQueue.push; queue.splice = FixedQueue.splice; queue.unshift = FixedQueue.unshift; // Trim any initial excess from the queue. FixedQueue.trimTail.call( queue ); // Return the new queue. return( queue ); } // I trim the queue down to the appropriate size, removing // items from the beginning of the internal array. FixedQueue.trimHead = function(){ // Check to see if any trimming needs to be performed. if (this.length <= this.fixedSize){ // No trimming, return out. return; } // Trim whatever is beyond the fixed size. Array.prototype.splice.call( this, 0, (this.length - this.fixedSize) ); }; // I trim the queue down to the appropriate size, removing // items from the end of the internal array. FixedQueue.trimTail = function(){ // Check to see if any trimming needs to be performed. if (this.length <= this.fixedSize){ // No trimming, return out. return; } // Trim whatever is beyond the fixed size. Array.prototype.splice.call( this, this.fixedSize, (this.length - this.fixedSize) ); }; // I synthesize wrapper methods that call the native Array // methods followed by a trimming method. FixedQueue.wrapMethod = function( methodName, trimMethod ){ // Create a wrapper that calls the given method. var wrapper = function(){ // Get the native Array method. var method = Array.prototype[ methodName ]; // Call the native method first. var result = method.apply( this, arguments ); // Trim the queue now that it's been augmented. trimMethod.call( this ); // Return the original value. return( result ); }; // Return the wrapper method. return( wrapper ); }; // Wrap the native methods. FixedQueue.push = FixedQueue.wrapMethod( "push", FixedQueue.trimHead ); FixedQueue.splice = FixedQueue.wrapMethod( "splice", FixedQueue.trimTail ); FixedQueue.unshift = FixedQueue.wrapMethod( "unshift", FixedQueue.trimTail );