JSFiddle - React, Tailwind, and code Playground

JavaScript

var data = {
    "store": {
        "book": [{
            "category": "reference",
                "author": "Nigel Rees",
                "title": "Sayings of the Century",
                "price": 8.95
        }, {
            "category": "fiction",
                "author": "Evelyn Waugh",
                "title": "Sword of Honour",
                "price": 12.99
        }],
            "bicycle": {
            "color": "red",
                "price": 19.95
        }
    }
}
var path = "store>book>0>price"


    function updateObject(data, path, value) {
        var pathArray = path.split(">");
        var pointer = data; // points to the current nested object
        for (var i = 0, len = pathArray.length; i < len; i++) {
            var path = pathArray[i];
            if (pointer.hasOwnProperty(path)) {
                if (i === len - 1) {
                    pointer[path] = value;
                } else {
                    pointer = pointer[path];
                }
            } else {
                // throw error or terminate. The path is incorrect
            }
        }
    }

updateObject(data, path, "10.00");

console.log(data)