javascript - How to obtain a master structure for a json file?

Question

I have a JSON file as follows:

[
    {
        "dog": "lmn",
        "tiger": [
            {
                "bengoltiger": {
                    "height": {
                        "x": 4
                    }
                },
                "indiantiger": {
                    "paw": "a",
                    "foor": "b"
                }
            },
            {
                "bengoltiger": {
                    "width": {
                        "a": 8
                    }
                },
                "indiantiger": {
                    "b": 3
                }
            }
        ]
    },
    {
        "dog": "pqr",
        "tiger": [
            {
                "bengoltiger": {
                    "width": {
                        "m": 3
                    }
                },
                "indiantiger": {
                    "paw": "a",
                    "foor": "b"
                }
            },
            {
                "bengoltiger": {
                    "height": {
                        "n": 8
                    }
                },
                "indiantiger": {
                    "b": 3
                }
            }
        ],
        "lion": 90
    }
]

I want to transform this to obtain all possible properties of any object at any nesting level. For arrays, the first object should contain all the properties. The values are trivial, but the below solution considers the first encountered value for any property. (For ex. "lmn" is preserved for the "dog" property) Expected output:

[
    {
        "dog": "lmn",
        "tiger": [
            {
                "bengoltiger": {
                    "height": {
                        "x": 4,
                        "n": 8
                    },
                    "width": {
                        "a": 8,
                        "m": 3
                    }
                },
                "indiantiger": {
                    "paw": "a",
                    "foor": "b",
                    "b": 3
                }
            }
        ],
        "lion": 90
    }
]

Here's a recursive function I tried before this nesting problem struck me

function consolidateArray(json) {
    if (Array.isArray(json)) {
      const reference = json[0];
      json.forEach(function(element) {
        for (var key in element) {
          if (!reference.hasOwnProperty(key)) {
            reference[key] = element[key];
          }
        }
      });
      json.splice(1);
      this.consolidateArray(json[0]);
    } else if (typeof json === 'object') {
      for (var key in json) {
        if (json.hasOwnProperty(key)) {
          this.consolidateArray(json[key]);
        }
      }
    }
  };
  
var json = [
    {
        "dog": "lmn",
        "tiger": [
            {
                "bengoltiger": {
                    "height": {
                        "x": 4
                    }
                },
                "indiantiger": {
                    "paw": "a",
                    "foor": "b"
                }
            },
            {
                "bengoltiger": {
                    "width": {
                        "a": 8
                    }
                },
                "indiantiger": {
                    "b": 3
                }
            }
        ]
    },
    {
        "dog": "pqr",
        "tiger": [
            {
                "bengoltiger": {
                    "width": {
                        "m": 3
                    }
                },
                "indiantiger": {
                    "paw": "a",
                    "foor": "b"
                }
            },
            {
                "bengoltiger": {
                    "height": {
                        "n": 8
                    }
                },
                "indiantiger": {
                    "b": 3
                }
            }
        ],
        "lion": 90
    }
];
consolidateArray(json);
alert(JSON.stringify(json, null, 2));

Answer 1

General logic using this new JNode IIFE with comments - ask someone more clever if you do not understand something as me ;-)

And level starts from 1 as there is no root object @start.

var json;
function DamnDemo() {
    json = DemoJSON();
    var it = new JNode(json), it2 = it;
    var levelKeys = []; /* A bit crazy structure:
    [
      levelN:{
               keyA:[JNode, JNode,...],
               keyB:[JNode, JNode,...],
               ...
             },
      levelM:...
    ]
    */
    do {
        var el = levelKeys[it.level]; // array of level say LevelN or undefined
        el = levelKeys[it.level] = el || {}; // set 2 empty it if does not exist
        el = el[it.key] = el[it.key] || []; // key array in say levelN
        el.push(it); // save current node indexing by level, key -> array
    } while (it = it.DepthFirst()) // traverse all nodes
    for(var l1 in levelKeys) { // let start simply by iterating levels
        l2(levelKeys[l1]);
    }
    console.log(JSON.stringify(json, null, 2));
}

function l2(arr) { // fun starts here...
    var len = 0, items = []; // size of arr, his items to simple Array
    for(var ln in arr) { // It's a kind of magic here ;-) Hate recursion, but who want to rewrite it ;-)
        if (arr[ln] instanceof JNode) return 1; // End of chain - our JNode for traverse of length 1
        len += l2(arr[ln]);
        items.push(arr[ln]);
    }
    if (len == 2) { // we care only about 2 items to move (getting even 3-5)
        //console.log(JSON.stringify(json));
        if (!isNaN(items[0][0].key) || (items[0][0].key == items[1][0].key)) { // key is number -> ignore || string -> must be same
            console.log("Keys 2B moved:", items[0][0].key, items[1][0].key, "/ level:", items[0][0].level);
            var src = items[1][0]; // 2nd similar JNode
            moveMissing(items[0][0].obj, src.obj); // move to 1st
            //console.log(JSON.stringify(json));
            if (src.level == 1) { // top level cleaning
                delete src.obj;
                delete json[src.key]; // remove array element
                if (!json[json.length-1]) json.length--; // fix length - hope it was last one (there are other options, but do not want to overcomplicate logic)
            } else {
                var parent = src.parent;
                var end = 0;
                for(var i in parent.obj) {
                    end++;
                    if (parent.obj[i] == src.obj) { // we found removed in parent's array
                        delete src.obj; // delete this empty object
                        delete parent.obj[i]; // and link on
                        end = 1; // stupid marker
                    }
                }
                if (end == 1 && parent.obj instanceof Array) parent.obj.length--; // fix length - now only when we are on last element
            }
        } else console.log("Keys left:", items[0][0].key, items[1][0].key, "/ level:", items[0][0].level); // keys did not match - do not screw it up, but report it
    }
    return len;
}

function moveMissing(dest, src) {
    for(var i in src) {
        if (src[i] instanceof Object) {
            if (!dest[i]) { // uff object, but not in dest
                dest[i] = src[i];
            } else { // copy object over object - let it bubble down...
                moveMissing(dest[i], src[i]);
            }
            delete src[i];
        } else { // we have value here, check if it does not exist, move and delete source
            if (!dest[i]) {
                dest[i] = src[i];
                delete src[i];
            }
        }
    }
}

// JSON_Node_Iterator_IIFE.js
'use strict';
var JNode = (function (jsNode) {

    function JNode(json, parent, pred, key, obj, fill) {
        var node, pred = null;
        if (parent === undefined) {
            parent = null;
        } else if (fill) {
            this.parent = parent;
            this.pred = pred;
            this.node = null;
            this.next = null;
            this.key = key;
            this.obj = obj;
            return this;
        }
        var current;
        var parse = (json instanceof Array);
        for (var child in json) {
            if (parse) child = parseInt(child);
            var sub = json[child];
            node = new JNode(null, parent, pred, child, sub, true);
            if (pred) {
                pred.next = node;
                node.pred = pred;
            }
            if (!current) current = node;
            pred = node;
        }
        return current;
    }

    JNode.prototype = {
        get hasNode() {
            if (this.node) return this.node;
            return (this.obj instanceof Object);
        },
        get hasOwnKey() { return this.key && (typeof this.key != "number"); },
        get level() {
            var level = 1, i = this;
            while(i = i.parent) level++;
            return level;
        },
        Down: function() {
            if (!this.node && this.obj instanceof Object) {
                this.node = new JNode(this.obj, this);
            }
            return this.node;
        },
        Stringify: function() { // Raw test stringify - #s are taken same as strings
            var res;
            if (typeof this.key == "number") {
                res = '[';
                var i = this;
                do {
                    if (i.node) res += i.node.Stringify();
                    else res += "undefined";
                    i = i.next;
                    if (i) res += ','
                } while(i);
                res += ']';
            } else {
                res = '{' + '"' + this.key + '":';
                res += (this.node?this.node.Stringify():this.hasNode?"undefined":'"'+this.obj+'"');
                var i = this;
                while (i = i.next) {
                    res += ',' + '"' + i.key + '":';
                    if (i.node) res += i.node.Stringify();
                    else {
                        if (i.obj instanceof Object) res += "undefined";
                        else res += '"' + i.obj + '"';
                    }
                };
                res += '}';
            }
            return res;
        },
        DepthFirst: function () {
            if (this == null) return 0; // exit sign
            if (this.node != null || this.obj instanceof Object) {
                return this.Down(); // moved down
            } else if (this.next != null) {
                return this.next;// moved right
            } else {
                var i = this;
                while (i != null) {
                    if (i.next != null) {
                        return i.next; // returned up & moved next
                    }
                    i = i.parent;
                }
            }
            return 0; // exit sign
        }
    }

    return JNode;
})();

// Fire test
DamnDemo();
function DemoJSON() {
    return [
    {
        "dog": "lmn",
        "tiger": [
            {
                "bengoltiger": {
                    "height": {
                        "x": 4
                    }
                },
                "indiantiger": {
                    "paw": "a",
                    "foor": "b"
                }
            },
            {
                "bengoltiger": {
                    "width": {
                        "a": 8
                    }
                },
                "indiantiger": {
                    "b": 3
                }
            }
        ]
    },
    {
        "dog": "pqr",
        "tiger": [
            {
                "bengoltiger": {
                    "width": {
                        "m": 3
                    }
                },
                "indiantiger": {
                    "paw": "a",
                    "foor": "b"
                }
            },
            {
                "bengoltiger": {
                    "height": {
                        "n": 8
                    }
                },
                "indiantiger": {
                    "b": 3
                }
            }
        ],
        "lion": 90
    }
]
;}