Improprove the efficiency of flattening an array containing nested JSON objects using JavaScript

Question

Improprove the efficiency of flattening an array containing nested JSON objects using JavaScript

Supposed to be an array structured like this:

[
     {
        "key_set1": {
            int_val: 3,
            arr_val: [
                1,
                3,
                4
            ]
        }
    },
    {
        "key_set2": {
            string_val: "foo"
        }
    }
  ]

I aim to flatten the inner object keys into a new root object, resulting in:

{
    "key_set1": {
        "int_val": 3,
        "arr_val": [
            1,
            3,
            4
        ]
    },
    "key_set2": {
        "string_val": "foo"
    }
}

Considerations:

The nested structure may have N levels with N > 10
The structure is valid JSON not Javascript object (atomit/non-atomic types)
The input json file can be large (hundreds of KBytes)
Must use JavaScript V8 / ECMAScript6 for processing
Processing time needs to be within milliseconds
Variants of this mapping will involve parsing input JSON and modifying values using methods like map

I seek the most optimized solution utilizing built-in methods such as forEach, fast iterators for, while, etc., for optimal performance in best/worst cases.

javascript json flatten

Answer 1

Answer №1

From my understanding, you prefer to swap out the array with an object and use the first level key as the new key for the resulting object.

let arr = [{ "key_set1": { int_val: 3, arr_val: [1, 3, 4] } }, { "key_set2": { string_val: "foo" } }],
    obj = {};

arr.forEach(function (a) {
    let key = Object.keys(a)[0];
    obj[key] = a[key];
});

console.log(obj);

Answer 2

From my understanding, you prefer to swap out the array with an object and use the first level key as the new key for the resulting object.

let arr = [{ "key_set1": { int_val: 3, arr_val: [1, 3, 4] } }, { "key_set2": { string_val: "foo" } }],
    obj = {};

arr.forEach(function (a) {
    let key = Object.keys(a)[0];
    obj[key] = a[key];
});

console.log(obj);

Answer 3

Answer №2

If you are aiming to achieve the best optimization for your code, it is advisable not to utilize Array.map in this scenario since it generates a new array. Instead, opt to swiftly iterate through the list array and populate the new flattened object. Here is an example of an "optimized" solution:

var flattened = {}, len = list.length;
while (len--) {
    Object.keys(list[len]).forEach((k) => (flattened[k] = list[len][k]));
}
console.log(JSON.stringify(flattened, 0, 4));

The resulting output will be:

{
    "key_set2": {
        "string_val": "foo"
    },
    "key_set1": {
        "int_val": 3,
        "arr_val": [
            1,
            3,
            4
        ]
    }
}

Answer 4

If you are aiming to achieve the best optimization for your code, it is advisable not to utilize Array.map in this scenario since it generates a new array. Instead, opt to swiftly iterate through the list array and populate the new flattened object. Here is an example of an "optimized" solution:

var flattened = {}, len = list.length;
while (len--) {
    Object.keys(list[len]).forEach((k) => (flattened[k] = list[len][k]));
}
console.log(JSON.stringify(flattened, 0, 4));

The resulting output will be:

{
    "key_set2": {
        "string_val": "foo"
    },
    "key_set1": {
        "int_val": 3,
        "arr_val": [
            1,
            3,
            4
        ]
    }
}

Improprove the efficiency of flattening an array containing nested JSON objects using JavaScript

Answer №1

Answer №2

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