Iterate over multidimensional array, filter and create new one in javascript

Question

I found this post but it's not really what I'm looking for. I have a huge JSON file with this structure:

{
    foo: [1, 2, 3, ...],
    bar: [
        {
            name: 'abc',
            cl: 2,
            data: [
                      [[2, 4, 6], [4, 5, 6]],
                      [[5, 3, 5], [5, 7, 9]],
                      [[6, 8, 9], [6, 8, 9]],
                      ...
                  ]
        },
        {
            name: 'def',
            cl: 1,
            data: [10, 20, 30, ...]
        }
    ]
}

I have a class representing the object and I can extract the properties and the objects inside the parent object. The foo property is mandatory while the bar property is optional. data is a numeric array that can be 1D or 3D. The foo.length and the data.length are always the same. I want to reduce the file size (in term of contents) but keeping the same structure, i.e. copy the old object to a new with exactly the same structure but shorter, so I could define a smaller length or range and get a new object, e.g. if I say to go from foo[0] to foo[1] then the data property will also go from data[0] to data[1] in the new object.

Is this possible? If yes, how can I achieve it? Maybe with map? but how?

function filter(obj, from, to){
     /// ?
}

Regards.

EDIT:

The new reduced object should be something like this:

{
    foo: [1, 2],
    bar: [
    {
        name: 'abc',
        cl: 2,
        data: [
                  [[2, 4, 6], [4, 5, 6]],
                  [[5, 3, 5], [5, 7, 9]]
              ]
    },
    {
        name: 'def',
        cl: 1,
        data: [10, 20]
    }
]
}

No, I should be able to take the elements from a point to another, so in this example, I want to go from foo[0] to foo[1]. But it could be any range inside the length of the foo.length. That will also affect the elements taken from data: foo.length = (bar with name 'abc').data.length = (bar with name 'def').data.length And foo[i] is related with (bar with name 'abc').data[i] and (bar with name 'def').data[i] — Macondiana
– Macondiana, Commented Nov 7, 2016 at 9:51

Nina Scholz · Accepted Answer · 2016-11-07 09:44:32Z

1

You could use Array#slice for it.

function slice(obj, from, to) {
    obj.foo = obj.foo.slice(from, to + 1);
    obj.bar.forEach(function (a) {
        a.data = a.data.slice(from, to + 1);
    });
}

var object = { foo: [1, 2, 3], bar: [{ name: 'abc', cl: 2, data: [[[2, 4, 6], [4, 5, 6]], [[5, 3, 5], [5, 7, 9]], [[6, 8, 9], [6, 8, 9]], ] }, { name: 'def', cl: 1, data: [10, 20, 30] }] };

slice(object, 0, 1);
console.log(object);

.as-console-wrapper { max-height: 100% !important; top: 0; }

answered Nov 7, 2016 at 9:44

Nina Scholz

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