数据结构队列Queue

function Queue() {
  // 数据存储
  this.dataStore = [];

}
Queue.prototype = {
  constructor: Queue,add: function(array) {
    this.dataStore = array;
  },// 排列
  enqueue: function( element ) {
    this.dataStore.push( element );
  },//随即读取
  randomData: function() {
    var index  = Math.floor(Math.random() * (this.length()-1));
    if ( index < 0 ) {
      //index = 0;
    }
    return this.dataStore.splice(index,1);
  },// 出列
  dequeue: function() {
   return this.dataStore.shift();
  },// 读取队首
  front: function() {
    return this.dataStore[0];
  },// 读取队尾
  back: function() {
    return this.dataStore[this.dataStore.length - 1];
  },// 显示队列内所有元素
  toString: function() {
    var retStr = "";
    for ( var i = 0,length = this.dataStore.length; i< len; i++ ) {
      retStr +=  "src:" + this.dataStore[i].src + " city:" + this.dataStore[i].city + " position: " + this.dataStore[i].position;
    }
    return retStr;
  },// 判断队列是否为空
  empty: function() {
    if ( this.dataStore.length == 0 ) {
      return true;
    } else {
      return false;
    }
  },length: function() {
    return this.dataStore.length;
  }
};