JavaScript array manipulation

I am working with an array of objects that have a year and count property like this:

[{year: "1920", count: 0}, {year: "1921", count: 2}, {year: "1925", count: 0}, {year: "1930", count: 21}, ....]

My goal is to populate all the years between a starting year (e.g. 1900) and an ending year (e.g. 2000) in the array with objects like {year: -year-, count: 0}. For example, filling in the years between 1900 and 1920, 1921 and 1925, 1925 and 1930, and 1930 and 2000.

If anyone has encountered a similar issue and can offer some guidance, I would greatly appreciate it!

Edit: So far, I have attempted a simple for loop, checking each iteration if the year is in the array. However, I believe there may be a more efficient and effective solution to this problem.

javascriptarrays

Answer №1

To start, you can initialize an object using the current years array and then create a new array by checking if the year is present in that object:

const presentYear = [{year: "1920", count: 0}, {year: "1921", count: 2}, {year: "1925", count: 0}, {year: "1930", count: 21}];

const presentYearObj = Object.fromEntries(presentYear.map(k=>[k.year, k]));

const allData = Array.from({length:101}, (_,i)=>presentYearObj[`${1900+i}`] || ({year:`${1900+i}`, count:0}));

console.log(allData);

Answer №2


let years =
    [
        {year: "1920", count: 0},
        {year: "1921", count: 2},
        {year: "1925", count: 0},
        {year: "1930", count: 21}
    ]

let yearNumbers = years.map(item => {
    return +item.year
})

console.log(yearNumbers)

for (let j = 1900; j < 2000; j++) {
    if (!yearNumbers.includes(j)) {
        years.push({year: j + '', count: 0})
    }
}

console.log(years.length)

Answer №3

function generateYearCounts(startYear, endYear, existingData) {
  
  let existingCounts = {};
  existingData.map(item => existingCounts[item.year] = item.count);
  
  let yearsData = [];
  for (let year = startYear; year <= endYear; year++) {
    yearsData.push({ 
      year: year.toString(), 
      count: existingCounts[year] || 0
    });
  }
  
  return yearsData;
  
}

let existingYearsData = [
        { year: "1920", count: 0},
        { year: "1921", count: 5},
        { year: "1925", count: 0},
        { year: "1930", count: 10}
  ];

existingYearsData = generateYearCounts(1900, 2000, existingYearsData);
console.log( existingYearsData );

This function constructs a new array by filling in the count values based on the existing data array.

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