06-kiryana-store.js

1/**
2 * 🏪 Kiryana Store Bill - Array Transform
3 *
4 * Gupta ji ki kiryana (grocery) store hai. Monthly hisaab kitaab karna hai —
5 * items ka total nikalna, sorting karna, bill format karna.
6 * Array transform methods se Gupta ji ki dukaan digital banao!
7 *
8 * Data format: items = [
9 *   { name: "Atta", price: 40, qty: 2 },
10 *   { name: "Daal", price: 80, qty: 1 },
11 *   ...
12 * ]
13 *
14 * Methods to explore: .map(), .filter(), .reduce(), .sort(), .join()
15 *
16 * Functions:
17 *
18 *   1. getItemNames(items)
19 *      - .map() se sirf names nikalo
20 *      - Agar items array nahi hai, return []
21 *      - Example: getItemNames([{name:"Atta",price:40,qty:2}]) => ["Atta"]
22 *
23 *   2. getAffordableItems(items, maxPrice)
24 *      - .filter() se items nikalo jinka price <= maxPrice
25 *      - Agar items array nahi hai ya maxPrice number nahi hai, return []
26 *      - Example: getAffordableItems([{name:"Atta",price:40},{name:"Ghee",price:500}], 100)
27 *                 => [{name:"Atta",price:40}]
28 *
29 *   3. calculateTotal(items)
30 *      - .reduce() se (price * qty) ka sum nikalo
31 *      - Agar items array nahi hai ya empty hai, return 0
32 *      - Example: calculateTotal([{name:"Atta",price:40,qty:2},{name:"Daal",price:80,qty:1}])
33 *                 => 160
34 *
35 *   4. sortByPrice(items, ascending)
36 *      - [...items].sort() se NEW sorted array return karo (original mat badlo!)
37 *      - ascending = true => low to high, false => high to low
38 *      - Agar items array nahi hai, return []
39 *      - Example: sortByPrice([{name:"Ghee",price:500},{name:"Atta",price:40}], true)
40 *                 => [{name:"Atta",price:40},{name:"Ghee",price:500}]
41 *
42 *   5. formatBill(items)
43 *      - .map() se har item ko "name x qty = Rs.total" format karo
44 *      - Phir .join("\n") se multi-line bill banao
45 *      - Agar items array nahi hai ya empty hai, return ""
46 *      - Example: formatBill([{name:"Atta",price:40,qty:2}]) => "Atta x 2 = Rs.80"
47 *
48 * @example
49 *   getItemNames([{name:"Atta",...}])         // => ["Atta"]
50 *   calculateTotal([{price:40,qty:2},...])    // => 160
51 *   formatBill([{name:"Atta",price:40,qty:2}]) // => "Atta x 2 = Rs.80"
52 */
53export function getItemNames(items) {
54  if(!Array.isArray(items)){
55    return []
56  }
57  return items.map(item => item.name)
58}
59
60export function getAffordableItems(items, maxPrice) {
61  if(!Array.isArray(items) || typeof maxPrice !== "number"){
62    return []
63  }
64  return items.filter(item => item.price <= maxPrice)
65}
66
67export function calculateTotal(items) {
68  
69  if(!Array.isArray(items) || items.length == 0){
70    return 0
71  }
72
73  return items.reduce(
74    (total, item) => total + item.price * item.qty,
75    0
76  );
77}
78
79export function sortByPrice(items, ascending) {
80
81  if(!Array.isArray(items)){
82    return []
83  }
84  
85  return [...items].sort((a, b) =>
86    ascending ? a.price - b.price : b.price - a.price
87  );
88}
89
90export function formatBill(items) {
91 
92  if(!Array.isArray(items) || items.length == 0){
93    return ""
94  }
95
96 return items
97    .map(item => `${item.name} x ${item.qty} = Rs.${item.price * item.qty}`)
98    .join("\n");
99    
100}
101