如何使用javascript填充数组中缺少的月份

Question

Is there a way how can i complete missing month and sale in an incomplete array.

sometimes i get a query like this:

var sales = [

    {'month': '04', 'sale': 126},
    {'month': '06', 'sale': 165},
    {'month': '07', 'sale': 10},
    {'month': '08', 'sale': 20},
    {'month': '09', 'sale': 211},
    {'month': '10', 'sale': 27},
    {'month': '11', 'sale': 112},
];

and i need to add the missing months with sale: 0.

I thought i can make a second array with all months and then compare this two arrays and pick the duplicates to the array with all months:

var compareArray = [

    {'month': '01', 'sale': 0},
    {'month': '02', 'sale': 0},
    {'month': '03', 'sale': 0},
    {'month': '04', 'sale': 0},
    {'month': '05', 'sale': 0},
    {'month': '06', 'sale': 0},
    {'month': '07', 'sale': 0},
    {'month': '08', 'sale': 0},
    {'month': '09', 'sale': 0},
    {'month': '10', 'sale': 0},
    {'month': '11', 'sale': 0},
    {'month': '12', 'sale': 0},
];

Answer 1

Instead of pre-defining the 12-entries array, you could use Array(12).keys() and use Array.from to map that to the desired output:

 var sales = [{'month': '04', 'sale': 126}, {'month': '06', 'sale': 165}, {'month': '07', 'sale': 10}, {'month': '08', 'sale': 20}, {'month': '09', 'sale': 211}, {'month': '10', 'sale': 27}, {'month': '11', 'sale': 112}]; sales = Array.from(Array(12).keys(), month => sales.find(sale => +sale.month === month+1) || { month: ("0"+(month+1)).substr(-2), sale: 0 } ); console.log(sales); 

Answer 2

An approach based on .map and .find array methods

const data = [
    {'month': '04', 'sale': 126},
    {'month': '06', 'sale': 165},
    {'month': '07', 'sale': 10},
    {'month': '08', 'sale': 20},
    {'month': '09', 'sale': 211},
    {'month': '10', 'sale': 27},
    {'month': '11', 'sale': 112},
];

const result = [...Array(12)].map((m, i) => {
  const month = i < 9 ? '0' + (i + 1) : String(i + 1);
  return data.find(d => d.month === month) || { month, sale: 0 };
});

Answer 3

You can use a simple for loop then Array.sort() to get the desired output:

 var sales = [{ 'month': '04', 'sale': 126 }, { 'month': '06', 'sale': 165 }, { 'month': '07', 'sale': 10 }, { 'month': '08', 'sale': 20 }, { 'month': '09', 'sale': 211 }, { 'month': '10', 'sale': 27 }, { 'month': '11', 'sale': 112 }, ]; for (var i = 1; i <= 12; i++) { var existObj = sales.find(item => +item.month === i); if (!existObj) { sales.push({ 'month': i > 9 ? i : '0' + i, 'sale': 0 }); } } sales.sort(function(a, b) { return +a.month - +b.month; }); console.log(sales); 

Answer 4

Because your month numbers are numbers, and span a convenient range, you can use them as array indexes:

var yearSales = sales.reduce(function(rv, month) {
  a[parseInt(month.month, 10)] = month;
  return a;
}, []);

Then you can find the empty slots:

for (let i = 0; i < 12; i++)
  if (!yearSales[i])
    yearSales[i] = { month: i, sales: 0 };

(I didn't use .forEach() because it skips empty slots, and those are the ones I want to target.)

Answer 5

You can use the same approach I used below. Bascially just loop 1 - 12 and if you find missing months, add them to the array. Once you have all your months in the array, simply sort in ascending order based on month number.

 const sales = [{ 'month': '04', 'sale': 126 }, { 'month': '06', 'sale': 165 }, { 'month': '07', 'sale': 10 }, { 'month': '08', 'sale': 20 }, { 'month': '09', 'sale': 211 }, { 'month': '10', 'sale': 27 }, { 'month': '11', 'sale': 112 } ]; function generateSalesReport(salesData) { const monthsWithSales = []; const salesReport = []; salesData.forEach(el => { monthsWithSales.push(Number.parseInt(el.month)); salesReport.push(el); }); //Fill in the missing months for (let i = 1; i <= 12; i++) { if (monthsWithSales.indexOf(i) === -1) { let monthStr = i.toString(); salesReport.push({ 'month': monthStr.length < 2 ? '0' + monthStr : monthStr, 'sale': 0 }); } } //Sort the sales report array return salesReport.sort((a, b) => parseInt(a.month) - parseInt(b.month)); } console.log(generateSalesReport(sales));