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Accepted
yiha
Asked: 2022-09-05 07:02:17 +0800 CST 2022-09-05 07:02:17 +0800 CST

How to create a new object using as keys the values ​​of a property contained in several objects of a multidimensional array

  • 772

I want the empty object filteredProducts{}to return tech and food as key but it returns empty, and I don't know where the error is.

function sortProducts(matrix) {
  //declaro las variables
  const filteredProducts = {};
  let techArray = [];
  let foodArray = [];
  //bucle para recorrer el array input
  for (let i = 0; i < matrix.length; i++) {
    let products = matrix[i];
    //declaro las variables para asignarle los nuevos valores
    let category = products.product;
    let tech = category === "tech";
    //condicional que agrega el valor tech al array 
    if (tech) {
      techArray.push(products[i]);
      filteredProducts.tech = techArray;
    }
  }
  //bucle para recorrer el array input
  for (let i = 0; i < matrix.length; i++) {
    let products = matrix[i];
    //declaro las variables para asignarle los nuevos valores
    let category = products.product;
    let food = category === "food";
    //condicional que agrega el valor tech al array 
    if (food) {
      foodArray.push(products[i]);
      filteredProducts.food = foodArray;

    }
  }
  //retorno los valores en el array vacio
  return filteredProducts;
}

//este es el array de input

let matrix = [
  [{
    product: "MacBook",
    price: 1019,
    category: 'tech'
  },
   {
     product: "Cheerios",
     price: 5,
     category: 'food'
   },
  ],

  [{
    product: "Snickers",
    price: 1.5,
    category: 'food'
  },
   {
     product: "Air Pods",
     price: 129,
     category: 'tech'
   },
  ],

];
sortProducts(matrix);
javascript

1 Answers

  1. Best Answer

    Leaving aside the errors that you have in your code, which I have not been able to reproduce because it is an image, I propose this solution to what I think you want to obtain:

    function sortProducts(matrix) {
  const filteredProducts = {}
  for (let i = 0; i < matrix.length; i++) {
    for (let j = 0; j < matrix[i].length; j++) {
      if (filteredProducts[matrix[i][j].category] === undefined) {
        filteredProducts[matrix[i][j].category] = []
      }
      filteredProducts[matrix[i][j].category].push(matrix[i][j])
    }
  }
  return filteredProducts
}

let matrix = [
  [{
      product: "MacBook",
      price: 1019,
      category: 'tech'
    },
    {
      product: "Cheerios",
      price: 5,
      category: 'food'
    },
  ],

  [{
      product: "Snickers",
      price: 1.5,
      category: 'food'
    },
    {
      product: "Air Pods",
      price: 129,
      category: 'tech'
    },
  ],

];
console.log(sortProducts(matrix))

    Explanation:

    • Inside the first for, which takes each array from the matrix object and returns a series of two objects, I loop back through them one by one forin order to get to their properties.

    • I establish a conditional to assemble the desired output of the filteredProducts object , which must contain the two existing categories as keys, and for this I access them through matrix[i][j].category, which I am going to use to establish a new key in filteredProducts by writing it with this bracket syntax that May I:

    filteredProducts[matrix[i][j].category]

    and as the value of the key I am going to tell it that it is an array by means of this assignment:

    filteredProducts[matrix[i][j].category] = []
    • In this way, I can add to this new array of the key the objects that match the object category in each cycle, using push() with this instruction:
    filteredProducts[matrix[i][j].category].push(matrix[i][j])

    and so we are going to go through all the objects of all the arrays contained in the matrix and the new object is going to be created with its keys and its arrays in order, which, at the end of the cycles, we return with a return .

    • It can be said that this conditional:
    if (filteredProducts[matrix[i][j].category] === undefined) {
  filteredProducts[matrix[i][j].category] = []
}

    it is necessary to tell javascript that this key is an array the first time it tries to access it, because if the key does not exist yet it will be undefined . The rest of the cycles, if it already exists, will not overwrite it again but will skip that assignment.

    You will tell us if it is what you intended to do and it works for you or not.

    • 0