Question 219202 in Javascript Question posted in
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Group array by multiple key object in javascript

i have a question with javascript.
I have a array data like this:

myArray = [
  { productId: 1, tableId: 1 },
  { productId: 1, tableId: 2 },
  { productId: 2, tableId: 1 },
  { productId: 2, tableId: 2 },
  { productId: 2, tableId: 3 },
  { productId: 2, tableId: 4 },
  { productId: 3, tableId: 1 },
  { productId: 4, tableId: 1 },
];

I want to convert this into:

result = [
    {
        productIds: [1, 2],
        tableIds: [1, 2],
    },
    {
        productIds: [2],
        tableIds: [3, 4],
    },
     {
        productIds: [3, 4],
        tableIds: [1],
    }
]

How do I handle this? Thanks for your help.

Tags:

2

Answers


  1. 0 
    let myArray = [{
    productId: 1,
    tableId: 1
  },
  {
    productId: 1,
    tableId: 2
  },
  {
    productId: 2,
    tableId: 1
  },
  {
    productId: 2,
    tableId: 2
  },
  {
    productId: 2,
    tableId: 3
  },
  {
    productId: 2,
    tableId: 4
  },
  {
    productId: 3,
    tableId: 1
  },
  {
    productId: 4,
    tableId: 1
  },
];

function groupConvertor(myArray) {
  let obj = {};
  myArray.forEach((e, i) => {
    if (obj[e.productId]) {
      obj[e.productId] = [...obj[e.productId], ...[e.tableId]];
    } else {
      obj[e.productId] = [e.tableId]
    }
  });
  let arr = [];
  for (let x in obj) {
    let obj1 = {
      productIds: [Number(x)],
      tableIds: obj[x]
    }
    arr.push(obj1);
  }
  return arr;
}
console.log(groupConvertor(myArray));
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  2. 0

    The sort() method for arrays can take in custom function for sorting an array. Here’s what the MSDN documentation says about it:

    A function that defines the sort order. The return value should be a number whose sign indicates the relative order of the two elements: negative if a is less than b, positive if a is greater than b, and zero if they are equal. NaN is treated as 0. The function is called with the following arguments:

    a
    The first element for comparison. Will never be undefined.

    b
    The second element for comparison. Will never be undefined.

    Here’s an example of it, using the array from your code:

    let result = myArray.sort((a, b) => {
    if (a.tableId < b.tableId)
        return -1;
    else if (a.tableId > b.tableId)
        return 1;
    else
        return 0;

});
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