How can I combine 2 arrays key and value in JavaScript?-CodePudding

I'm building my first project, an expense tracking app with React Native. It's going very well.

I would like to concat the following 2 arrays.

[{"Day": "08/31/2022"}, {"Day": "09/01/2022"}, {"Day": "08/31/2022"}, {"Day": "08/31/2022"}, {"Day": "08/31/2022"}, {"Day": "08/31/2022"}]

[{"Amount": "40"}, {"Amount": "300"}, {"Amount": "1715"}, {"Amount": "250"}, {"Amount": "100"}, {"Amount": "200"}]

Final results should be:

[{"Day": "08/31/2022", "Amount": "40"}, {"Day": "09/01/2022","Amount": "300"}, {"Day": "08/31/2022","Amount": "1715"}, {"Day": "08/31/2022","Amount": "250"}, {"Day": "08/31/2022","Amount": "100"}, {"Day": "08/31/2022","Amount": "200"}]

My current code:

  const q = query(collection(db, "users"), where("moneda", "==", "$"));
  const unsubscribe = onSnapshot(q, (querySnapshot) => {
    const dolarCurrency = [];
    const months =[];
    querySnapshot.forEach((doc) => {
        dolarCurrency.push(doc.data().cantidad);
        months.push(doc.data().fecha)
    });

    const hash = months.map((Day) => ({ Day }));
    const hashDolar = dolarCurrency.map(( Amount ) => ({ Amount }))
  });

Everything is working fine, and I'm pulling live data from my firebase to convert it into a chart on React Native with Victory Native for all my personal expenses. So, this would be my last step.

Any help or advice is appreciated!

CodePudding user response：

You can use Array#map and object destructuring as follows:

const days = [{"Day": "08/31/2022"}, {"Day": "09/01/2022"}, {"Day": "08/31/2022"}, {"Day": "08/31/2022"}, {"Day": "08/31/2022"}, {"Day": "08/31/2022"}],

      amounts = [{"Amount": "40"}, {"Amount": "300"}, {"Amount": "1715"}, {"Amount": "250"}, {"Amount": "100"}, {"Amount": "200"}],
      
      output = days.map(({Day},i) => ({Day, ...amounts[i]}));
      
      console.log( output );

CodePudding user response：

Here's a workaround if you want to apply some validations or use fallback value in cases such as if one array has more items than the other one:

function combine(array1, array2) {
  // If either one is not an array or if both are empty, return an empty array.
  if (
    !Array.isArray(array1) ||
    !Array.isArray(array2) ||
    (!array1.length && !array2.length)
  ) {
    return [];
  }
  
  // If one array is empty, return the other one.
  if (array1.length && !array2.length) {
    return array1;
  }
  
  if (!array1.length && array2.length) {
    return array2;
  }

  let arrayToLoop = array1;
  let otherArray = array2;
  
  // If array2 has more items than array1, loop array2 instead.
  if (array2.length > array1.length) {
    arrayToLoop = array2;
    otherArray = array1;
  }
  
  return arrayToLoop.map((item, index) => {
    // Return the current item if it has no match.
    if (!otherArray[index]) {
      return item;
    }
    
    // Else, merge with otherArray's current item.
    return {
      ...item,
      ...otherArray[index],
    };
  })
}

console.log(combine(arr1, arr2))