Question 53200 in Javascript Question posted in
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Convert a complex dictionary into a set of arrays in Javascript

I have an flat object in javascript as

{
    top1: {
        obj1: {}
        obj2: {}
    }
    top2: {
        obj3: {}
        obj4: {}
    }
    top3: {
        obj5: {}
        obj6: {}
    }
}

and I would need to get out an array like

["top1","obj1"],["top1","obj2"],["top2","obj3"],["top2","obj4"],["top3","obj5"],["top3","obj6"]

I felt I could run a run a map as Object.keys(OBJ).map((key) => … but I ended in nothing.
Which method could be the best on this case?

Tags:

3

Answers


  1. 0

    You could take a flat map approach with entries and their keys.

    const
    data = { top1: { obj1: {}, obj2: {} }, top2: { obj3: {}, obj4: {} }, top3: { obj5: {}, obj6: {} } },
    result = Object
        .entries(data)
        .flatMap(([k, o]) => Object.keys(o).map(l => [k, l]));

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

    If you have deeper nested objects, you could take a recursive approach.

    const
    getKeys = object => Object
        .entries(object)
        .flatMap(([k, v]) => {
            if (!v || typeof v !== 'object') return [[k]];
            const nested = getKeys(v);
            return nested.length
                ? nested.map(a => [k, ...a])
                : [[k]];
        }),
    data = { top1: { obj1: {}, obj2: {} }, top2: { obj3: {}, obj4: {} }, top3: { obj5: {}, obj6: { obj7: {} } } },
    result = getKeys(data);

console.log(result);
    .as-console-wrapper { max-height: 100% !important; top: 0; }
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  2. 0

    One-liner:

    Object.keys(o).flatMap(k => Object.keys(o[k]).map(K => [k, K]));

    Reference: Array#flatMap()

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  3. 0

    Probably unnecessary non-recursive approach for unknown depth of nesting:

    const data = {
  top1: { obj1: {}, obj2: {} }, top2: { obj3: {}, obj4: {} }, top3: { obj5: {}, obj6: {} },
  top4: { mid1: { obj7: 'Three', obj8: 10 }, mid2: { obj9: null, obj10: [4, 5, 6] } }
};

const has_keys = (value) =>
  value && typeof value === 'object' && !Array.isArray(value) && Object.keys(value).length > 0;

const get_routes = (data) => {
  const result = [];
  const queue = [[[], data]];
  
  while(queue.length > 0) {
    const [keys, value] = queue.pop();
    
    if(has_keys(value)) {
      queue.push(...Object.entries(value).map( ([k, v]) => [[...keys, k], v] ));
    } else {
      result.push(keys);
    }
  }
  
  return result.reverse();
};

console.log(get_routes(data));
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