bidirectional queues in JavaScript

1. Concept

/*--------------definition and test code for the bidirectional queue class----------------*/functionQueue () { This. DataStore = [];  This. Enqueuefront =Enqueuefront;  This. Enqueueback =Enqueueback;  This. Dequeuefront =Dequeuefront;  This. Dequeueback =Dequeueback;  This. Front =Front;  This. Back =Back ;  This. toString =toString;  This. Empty =empty;}//The trailing queue is the addition of an element at the end of the arrayfunctionEnqueueback (Element) { This. Datastore.push (Element);}//to join the head is to add an element to the head of the arrayfunctionEnqueuefront (Element) { This. Datastore.splice (0,0, Element);}//The tail out of the queue is the last element of the delete arrayfunctionDequeueback () {return  This. Datastore.splice ( This. datastore.length-1, 1);}//The first element of the array is removed from the team.functionDequeuefront () {return  This. Datastore.shift ();}//Take out the first element of the arrayfunctionFront () {return  This. datastore[0];}//remove the last element of the arrayfunctionBack () {return  This. datastore[ This. datastore.length-1];}functiontoString () {varRetstr = "";  for(vari=0; i< This. datastore.length; ++i) {retstr+= This. Datastore[i] + "&nbsp;"    }    returnretstr;}//determine if the array is emptyfunctionempty () {if( This. Datastore.length = = 0){        return true; }Else{        return false; }    }//returns the number of elements in an arrayfunctioncount () {return  This. Datastore.length;}varQ =NewQueue (); Q.enqueuefront ("1"); Q.enqueuefront ("2"); Q.enqueueback ("3"); Q.enqueueback ("4");d Ocument.write (q.tostring ());d Ocument.write (' <br> '); Q.dequeuefront ();d ocument.write (q.tostring ());d Ocument.write (' <br> '); Q.dequeueback ();d ocument.write (q.tostring ());d Ocument.write (' <br> ');d Ocument.write (' <br> ');

Output results

2. Code implementation

/*---------------------------Determine if a string is a palindrome-------------------------*/functionIspalindrome (str) {varQueue =NewQueue ();  for(vari=0; i<str.length; i++) {Queue.enqueuefront (str[i]); }        varNewstr = "";  while(!Queue.empty ()) {Newstr+=Queue.dequeuefront ();    } document.write (NEWSTR); document.write (' <br> '); if(str = =newstr) {Document.writeln (str+ "is a palindrome"); }Else{Document.writeln (str+ "Not palindrome"); }}ispalindrome ("Racecar");d Ocument.write (' <br> '); Ispalindrome ("Helloword");

Output Result:

bidirectional queues in JavaScript