Read and set object by string path

script.js

Object.prototype.stringGet = function(string, object = this) {
    string = string.replace(/\[(\w+)]/g, '.$1'); // convert indexes to properties
    string = string.replace(/^\./, ''); // strip a leading dot
    const array = string.split('.');
    array.forEach((key) => {
        if (key in object) object = object[key];
    });
    return object;
}


/*!
 * Add items to an object at a specific path
 * (c) 2021 Chris Ferdinandi, MIT License, https://gomakethings.com
 * @param  {Object}       obj  The object
 * @param  {String|Array} path The path to assign the value to
 * @param  {*}            val  The value to assign
 */
Object.prototype.stringSet = function (path, val, obj = this) {
    /**
     * If the path is a string, convert it to an array
     * @param  {String|Array} path The path
     * @return {Array}             The path array
     */
    function stringToPath (path) {
        // If the path isn't a string, return it
        if (typeof path !== 'string') return path;
        // Create new array
        let output = [];
        // Split to an array with dot notation
        path.split('.').forEach(function (item) {
            // Split to an array with bracket notation
            item.split(/\[([^}]+)]/g).forEach(function (key) {
                // Push to the new array
                if (key.length > 0) output.push(key);
            });
        });
        return output;
    }

    // Convert the path to an array if not already
    path = stringToPath(path);

    // Cache the path length and current spot in the object
    let length = path.length;
    let current = obj;

    // Loop through the path
    path.forEach(function (key, index) {

        // Check if the assigned key should be an array
        let isArray = key.slice(-2) === '[]';
        // If so, get the true key name by removing the trailing []
        key = isArray ? key.slice(0, -2) : key;
        // If the key should be an array and isn't, create an array
        if (isArray && !Array.isArray(current[key])) current[key] = [];

        // If this is the last item in the loop, assign the value
        if (index === length -1) {
            // If it's an array, push the value
            // Otherwise, assign it
            if (isArray) current[key].push(val);
            else current[key] = val;
        }

        // Otherwise, update the current place in the object
        else {
            // If the key doesn't exist, create it
            if (!current[key]) current[key] = {};
            // Update the current place in the object
            current = current[key];
        }
    });
}

script.min.js

Object.prototype.stringGet=function(t,e=this){return(t=(t=t.replace(/\[(\w+)]/g,".$1")).replace(/^\./,"")).split(".").forEach(t=>{t in e&&(e=e[t])}),e},Object.prototype.stringSet=function(t,e,n=this){let r=(t=function(t){if("string"!=typeof t)return t;let e=[];return t.split(".").forEach(function(t){t.split(/\[([^}]+)]/g).forEach(function(t){t.length>0&&e.push(t)})}),e}(t)).length,i=n;t.forEach(function(t,n){let c="[]"===t.slice(-2);t=c?t.slice(0,-2):t,c&&!Array.isArray(i[t])&&(i[t]=[]),n===r-1?c?i[t].push(e):i[t]=e:(i[t]||(i[t]={}),i=i[t])})};