JS中的算法与数据结构之字典(Dictionary)实例详解

//字典类

function Dictionary () {
  this.dataStore = [];
  this.add = add;     // 添加元素
  this.find = find;    // 查找元素
  this.remove = remove;  // 删除元素
  this.count = count;   // 字典中元素个数
  this.showAll = showAll; // 显示字典元素
  this.clear = clear;   // 清空字典
}

//向字典添加元素

function add( key , value ){
  this.dataStore[key] = value;
}

//查找字典中的元素

function find( key ){
  return this.dataStore[key];
}

//删除一个元素

function remove( key ){
  if( this.dataStore[key] ) delete this.dataStore[key];
  else return 'Not Found';
}

//显示字典元素

function showAll () {
  for( var key in this.dataStore ){
    console.log( key + '->' + this.dataStore[key] );
  }
}

//实例化字典类

var directory = new Dictionary();

//添加元素

directory.add( 'Jack' , '138****5505' );
directory.add( 'Alice' , '156****6606');
directory.add( 'Tom' , '180****8808');

//显示字典

directory.showAll();     // Jack->138****5505
               // Alice->156****6606
               // Tom->180****8808
            
directory.remove( 'Tom' );
directory.showAll();     // Jack->138****5505
               // Alice->156****6606

//查看字典中元素的个数

function count(){
  var n = 0 ;
  for ( var key in this.dataStore ){
    ++n;
  }
  return n;
}

var nums = [ 0 , 1 , 2 ] ;

console.log(nums.length)    // 3

var directory = [];
directory['Jack'] = '138****5505';
directory['Alice'] = '156****6606';
directory['Tom'] = '180****8808';

console.log(directory.length)  // 0

//清空字典

function clear(){
  for( var key in this.dataStore ){
    delete this.dataStore[key];
  }
}

console.log(directory.count());   // 2
directory.clear();
console.log(directory.count());   // 0

//改造后的showAll

function showAll(){
  var sortKeys = Object.keys(this.dataStore).sort();
  for( var key in sortKeys ){
    console.log( sortKeys[key] + '->' + this.dataStore[sortKeys[key]] );
  }
}

// 重新打印上述字典

directory.showAll();    // Alice->156****6606
              // Jack->138****5505
              // Tom->180****8808

//sortKeys

["Alice", "Jack", "Tom"]