"Can someone help me figure out how to retrieve a smaller array? I can't seem to get

Question

"Can someone help me figure out how to retrieve a smaller array? I can't seem to get

I need help reducing an array.

My desired output should be [1,5,4], but unfortunately I am getting back an empty array.

let arr=[1,[2,3],4]
let newarr=[]
 
let myarr=()=>{
    for(i=0;i<3;i++){
        array=arr[i].reduce
        newarr.push(array)
        return newarr
    }
}

javascript arrays methods reduce

Answer 1

Answer №1

To successfully utilize array.reduce, you must pass a function to it and then actually execute the function, like shown below (where console.log is used to call it):

const arr = [1, [2, 3], 4];

const myArr = (arr) => {
  let newArray = [];
  arr.forEach((arrayItem) => {
    // Iterate through each item in the array
    if (Array.isArray(arrayItem)) {
      // Check if the item is an array that needs reduction
      newArray.push(
        arrayItem.reduce(function (previous, current) {
          return previous + current;
        })
      ); // Reduce array to a single value using a reducer function and add it to new array
    } else {
      newArray.push(arrayItem); // If not an array, push it as is to the new array
    }
  });
  return newArray;
};

console.log( myArr(arr) );

There are always more concise and elegant ways to achieve the same result. The solution above aims for readability, but a one-liner alternative would be:

const arr = [1, [2, 3], 4]
const newArr = arr.map(i=>Array.isArray(i)?i.reduce((a,b)=>a+b):i)
console.log(newArr)

Answer 2

To successfully utilize array.reduce, you must pass a function to it and then actually execute the function, like shown below (where console.log is used to call it):

const arr = [1, [2, 3], 4];

const myArr = (arr) => {
  let newArray = [];
  arr.forEach((arrayItem) => {
    // Iterate through each item in the array
    if (Array.isArray(arrayItem)) {
      // Check if the item is an array that needs reduction
      newArray.push(
        arrayItem.reduce(function (previous, current) {
          return previous + current;
        })
      ); // Reduce array to a single value using a reducer function and add it to new array
    } else {
      newArray.push(arrayItem); // If not an array, push it as is to the new array
    }
  });
  return newArray;
};

console.log( myArr(arr) );

There are always more concise and elegant ways to achieve the same result. The solution above aims for readability, but a one-liner alternative would be:

const arr = [1, [2, 3], 4]
const newArr = arr.map(i=>Array.isArray(i)?i.reduce((a,b)=>a+b):i)
console.log(newArr)

Answer 3

Answer №2

Array#reduce is a method specific to arrays that requires a function to be passed as an argument. You've defined a function, but have not invoked it.

To fix this issue, you can try the following:

let arr = [1, [2, 3], 4];
let newarr = [];
 
((array) => {
    for(let i=0; i < array.length; i++) {
        const el = array[i];
        const topush = Array.isArray(el) ? el.reduce((total, curr) => total + curr, 0) : el;
        newarr.push(topush)
    }
})( arr );

console.log( newarr );

Alternatively, you can achieve the same result using both Array#map and Array#reduce. The key in both cases is to identify when to apply the reduce method on the array elements:

const arr = [1, [2, 3], 4, [4, 5, 7]];

const newarr = arr.map(el => 
    Array.isArray(el) ? el.reduce((sum,cur) => sum + cur, 0) : el
);

console.log( newarr );

Answer 4

Array#reduce is a method specific to arrays that requires a function to be passed as an argument. You've defined a function, but have not invoked it.

To fix this issue, you can try the following:

let arr = [1, [2, 3], 4];
let newarr = [];
 
((array) => {
    for(let i=0; i < array.length; i++) {
        const el = array[i];
        const topush = Array.isArray(el) ? el.reduce((total, curr) => total + curr, 0) : el;
        newarr.push(topush)
    }
})( arr );

console.log( newarr );

Alternatively, you can achieve the same result using both Array#map and Array#reduce. The key in both cases is to identify when to apply the reduce method on the array elements:

const arr = [1, [2, 3], 4, [4, 5, 7]];

const newarr = arr.map(el => 
    Array.isArray(el) ? el.reduce((sum,cur) => sum + cur, 0) : el
);

console.log( newarr );

"Can someone help me figure out how to retrieve a smaller array? I can't seem to get

Answer №1

Answer №2

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