JSFiddle - React, Tailwind, and code Playground

JavaScript

var object = {
    d: [
        {
            value: 1
        }, {
            value: 2
        }, {
            value: 3
        }
    ]
};

setByPath(object, 'd.1.value', null);
setByPath(object, 'a.b.c', 123);

console.clear();
console.log(JSON.stringify(object, null, 4));



function setByPath(object, path, value) {
    if (!(path && typeof path === 'string')) {
        throw new Error('path is not valid');
    }

    path = path.split('.');

    path.forEach(function (key, i) {
        if (i < path.length - 1) {
            if (!object.hasOwnProperty(key)) {
                object[key] = {};
            }

            object = object[key];
        } else {
            object[key] = value;
        }
    });
}