How Can I Optimize Flattening and Unflattening Nested JavaScript Objects?

Unflattening and Flattening Nested JavaScript Objects: Optimized Implementations

The task of flattening and un-flattening complex JavaScript objects can be time-consuming. Here's a comprehensive analysis to optimize this operation:

The challenge: A JavaScript object needs to be flattened with "." as the delimiter for object keys and "[INDEX]" for arrays.

Initial solution: The provided code solves the problem but is relatively slow.

Faster implementation (using regular expressions): Bergi introduces a significantly faster implementation using regular expressions. It unflattens the object by iterating through the flattened properties and creating nested structures accordingly.

Fastest implementation (non-regex): Building on Bergi's concept, the provided implementation offers the fastest non-regex version. It assumes specific rules for key names, excluding integers at the start or periods within the name.

Improving unflattening performance: AaditMShah enhances the unflatten performance by employing inline path parsing instead of String.split in the nested loop.

Final code (unflatten):

Object.unflatten = function(data) {
    "use strict";
    if (Object(data) !== data || Array.isArray(data))
        return data;
    var regex = /\.?([^.\[\]]+)|\[(\d+)\]/g,
        resultholder = {};
    for (var p in data) {
        var cur = resultholder,
            prop = "",
            m;
        while (m = regex.exec(p)) {
            cur = cur[prop] || (cur[prop] = (m[2] ? [] : {}));
            prop = m[2] || m[1];
        }
        cur[prop] = data[p];
    }
    return resultholder[""] || resultholder;
};

Final code (flatten):

Object.flatten = function(data) {
    var result = {};
    function recurse (cur, prop) {
        if (Object(cur) !== cur) {
            result[prop] = cur;
        } else if (Array.isArray(cur)) {
             for(var i=0, l=cur.length; i<l; i++)
                 recurse(cur[i], prop + "[" + i + "]");
            if (l == 0)
                result[prop] = [];
        } else {
            var isEmpty = true;
            for (var p in cur) {
                isEmpty = false;
                recurse(cur[p], prop ? prop+"."+p : p);
            }
            if (isEmpty &amp;&amp; prop)
                result[prop] = {};
        }
    }
    recurse(data, "");
    return result;
};

These optimizations significantly improve the performance of flattening and un-flattening nested JavaScript objects while adhering to Browser compatibility requirements.

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