I'm struggling with looping through an array of arrays and returning a new array with the incremented value of the result.

Here's the concept:

let array1 = [array1, array2];
let array2 = [4000,5000,3000,6000];
let array3 = [3000, 15000, 9000, 1000];

let i = 0;
let newArray = []
while (i < array1.length) {
// how do I get the combined value in a new array so that newArray[0] = 7000, newArray[1] = 20000 etc.
}

Array1 comes from an API and is an unknown number of arrays.

CodePudding user response：

This should work for any number of sub arrays. Here it is assumed that array1 contains 4 arrays.

let array2 = [4000, 5000, 3000, 6000]
let array3 = [3000, 15000, 9000, 500]
let array4 = [5000, 15000, 4000, 2000]
let array5 = [6000, 25000, 5000, 8000]
let array1 = [array2, array3, array4, array5]

const result = array1.reduce((acc, curr) => {
  return acc.map((item, index) => item   curr[index])
})

console.log(result)

References:

• .reduce
• .map

CodePudding user response：

In case number of elements is dynamic then,

let array1 = [[4000, 5000, 3000, 6000], [3000, 15000, 9000, 1000, 2000, 3000], [1000], [3000, 15000, 9000, 1000, 2000, 3000, 1000, 10000]];

let index = 0;
let newArray = [];
let maxElements = Math.max(...array1.map(arr => arr.length));
let arrayLength = array1.length;


while (index < maxElements) {
    let total = 0;

    for (let arrayIndex = 0; arrayIndex < arrayLength; arrayIndex  ) {
        let element = array1[arrayIndex][index]
        if (element) total  = element;
    }

    newArray.push(total);
    index  ;
}

console.log(newArray)

CodePudding user response：

You may need a nested loop. So basically you will iterate array1 which holds both array2 and array3 and then in newArray you will see if specific index has a value. If so then you will add value with previous one

let array2 = [4000, 5000, 3000, 6000];
let array3 = [3000, 15000, 9000, 1000];
let array1 = [array2, array3];
let i = 0;
let newArray = []
while (i < array1.length) {
  for (let j = 0; j < array1[i].length; j  ) {
    // if index of new array is unoccupied then set a value there 
    if (!newArray[j]) {
      newArray[j] = array1[i][j]
    } else {
      // if index is occupied then add with previous value
      newArray[j] = newArray[j]   array1[i][j]

    }

  }
  i  ;
}
console.log(newArray)