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Accepted
Eduardo Jiménez
Asked: 2022-08-13 17:54:37 +0800 CST 2022-08-13 17:54:37 +0800 CST

JS: Get total sum of the length of a property in a JSON array in a single statement

  • 772

What I need is to add in a single statement all the lengths of an array which is a property that is found in all the JSON of a JSON array.

Let's take the following json as an example:

[
    {
      id: 1,
      element: [1, 2, 3]
    },
    {
      id: 2,
      element: [5]
    },
    {
      id: 3,
      element: []
    }
]

The statement should add [1, 2, 3].length + [5].length + [].lengthwhich should give 4. The problem is that I need to do it in a single statement, but I haven't been able to do it, I tried with reduce but it's not clear to me how it works.

const array = [
    {
      id: 1,
      element: [1, 2, 3]
    },
    {
      id: 2,
      element: [5]
    },
    {
      id: 3,
      element: []
    }
];

console.log(array.reduce((accumulator, current, idx) => accumulator + array[idx].element.length));

console.log(array.reduce((accumulator, current) => accumulator + current.element.length));

javascript

1 Answers

  1. Best Answer

    This would be the solution with reducer, as a second parameter you must add the value you want the reducer.

    const array = [
    {
      id: 1,
      element: [1, 2, 3]
    },
    {
      id: 2,
      element: [5]
    },
    {
      id: 3,
      element: []
    }
];

console.log(array.reduce((accumulator, current) => accumulator + current.element.length, 0));

    • 2