js data structures queue

javascript/queue.js

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+// QUEUE METHODS IN JAVASCRIPT
+// enqueue: Enter queue, add an element at the end.
+// dequeue: Leave queue, remove the front element and return it.
+// front: Get the first element.
+// isEmpty: Determine whether the queue is empty.
+// size: Get the number of element(s) in queue.
+
+
+// Array in JavaScript has some attributes of queue, so we can use array to construct an example for queue:
+
+function Queue() {
+  var collection = [];
+  this.print = function () {
+    console.log(collection);
+  }
+  this.enqueue = function (element) {
+    collection.push(element);
+  }
+  this.dequeue = function () {
+    return collection.shift();
+  }
+  this.front = function () {
+    return collection[0];
+  }
+
+  this.isEmpty = function () {
+    return collection.length === 0;
+  }
+  this.size = function () {
+    return collection.length;
+  }
+}
+
+// PRIORITY QUEUE
+// Queue has another advanced version. Allocate each element by priority and it will be sorted according to the priority level:
+
+function PriorityQueue() {
+  this.enqueue = function (element) {
+    if (this.isEmpty()) {
+      collection.push(element);
+    } else {
+      var added = false;
+      for (var i = 0; i < collection.length; i++) {
+        if (element[1] < collection[i][1]) {
+          collection.splice(i, 0, element);
+          added = true;
+          break;
+        }
+      }
+      if (!added) {
+        collection.push(element);
+      }
+    }
+  }
+}
+
+// Testing it out:
+
+var pQ = new PriorityQueue();
+pQ.enqueue([ gannicus , 3]);
+pQ.enqueue([ spartacus , 1]);
+pQ.enqueue([ crixus , 2]);
+pQ.enqueue([ oenomaus , 4]);
+pQ.print();
+
+
+// Result: logs
+
+// [
+//   [  spartacus , 1 ],
+//   [  crixus , 2 ],
+//   [  gannicus , 3 ],
+//   [  oenomaus , 4 ]
+// ]