// filter()
var foo = [0,1,2,3,4,5,6,7,8,9];

var foo1 = foo.filter(
 function(item) {
 return item >= 5
 }
);

console.log(foo1); // [5, 6, 7, 8, 9]

// 定義商品類
function Product(name, brand, price) {
 this.name = name; // 名稱
 this.brand = brand; // 品牌
 this.price = price; // 價格
}

// 商品篩選器
const ProductFilters = {
 /**
 * 區(qū)間類型篩選
 * @param {array<Product>} products
 * @param {array<{type: String, low: number, high: number}>} ranges
 */
 rangesFilter: function (products, ranges) { }

 /**
 * 選擇類型篩選
 * @param {array<Product>} products
 * @param {array<{type: String, value: String}>} chooses
 */
 choosesFilter: function (products, chooses) { }
}

// 區(qū)間類型條件結(jié)構(gòu)
ranges: [
 {
  type: 'price', // 篩選類型/字段
  low: 3000, // 最小值
  high: 6000 // 最大值
 }
 ]

/**
 * @param {array<Product>} products
 * @param {array<{type: String, low: number, high: number}>} ranges
 */
 rangesFilter: function (products, ranges) {
 if (ranges.length === 0) {
  return products;
 } else {
  /**
  * 循環(huán)多個區(qū)間條件，
  * 每種區(qū)間類型應(yīng)該只有一個，
  * 比如價格區(qū)間不會有1000-2000和4000-6000同時需要的情況
  */
  for (let range of ranges) {
  // 多個不同類型區(qū)間是與邏輯，可以直接賦值給自身
  products = products.filter(function (item) {
   return item[range.type] >= range.low && item[range.type] <= range.high;
  });
  }
  return products;
 }
 }

// 選擇類型條件結(jié)構(gòu)
chooses: [
 {
  type: 'brand',
  value: '華為'
 },
 {
  type: 'brand',
  value: '蘋果'
 }
 ]

/**
 * @param {array<Product>} products
 * @param {array<{type: String, value: String}>} chooses
 */
 choosesFilter: function (products, chooses) {
 let tmpProducts = [];
 if (chooses.length === 0) {
  tmpProducts = products;
 } else {
  /**
  * 選擇類型條件是或邏輯，使用數(shù)組連接concat
  */
  for (let choice of chooses) {
  tmpProducts = tmpProducts.concat(products.filter(function (item) {
   return item[choice.type].indexOf(choice.value) !== -1;
  }));
  }
 }
 return tmpProducts;
 }

function doFilter(products, conditions) {
 // 根據(jù)條件循環(huán)調(diào)用篩選器里的方法
 for (key in conditions) {
 // 判斷是否有需要的過濾方法
 if (ProductFilters.hasOwnProperty(key + 'Filter') && typeof ProductFilters[key + 'Filter'] === 'function') {
  products = ProductFilters[key + 'Filter'](products, Conditions[key]);
 }
 }
 return products;
}

// 將兩種大類的篩選條件放在同一個對象里
let Conditions = {
 ranges: [
 {
  type: 'price',
  low: 3000,
  high: 6000
 }
 ],
 chooses: [
 {
  type: 'brand',
  value: '華為'
 }
 ]
}

// 商品數(shù)組
const products = [
 new Product('華為榮耀9', '華為', 2299),
 new Product('華為P10', '華為', 3488),
 new Product('小米MIX2', '小米', 3599),
 new Product('小米6', '小米', 2499),
 new Product('小米Note3', '小米', 2499),
 new Product('iPhone7 32G', '蘋果', 4588),
 new Product('iPhone7 Plus 128G', '蘋果', 6388),
 new Product('iPhone8', '蘋果', 5888),
 new Product('三星Galaxy S8', '三星', 5688),
 new Product('三星Galaxy S7 edge', '三星', 3399),
];
// 篩選條件
let Conditions = {
 ranges: [
 {
  type: 'price',
  low: 3000,
  high: 6000
 }
 ],
 chooses: [
 {
  type: 'brand',
  value: '華為'
 },
 {
  type: 'brand',
  value: '蘋果'
 }
 ]
}

let result = doFilter(products, Conditions);
console.log(result);

let Conditions = {
 ranges: [
 {
  type: 'price',
  low: 3000,
  high: 6000
 }
 ],
 chooses: [
 {
  type: 'name',
  value: 'iPhone'
 }
 ]
}