JSFiddle - React, Tailwind, and code Playground

JavaScript

var record = { 
    foo: { 
        bar: { baz: 0 } 
    },
    qux: {
        qaz: ''
    }
};

assignProperty(record, "foo.bar.baz", 4);
assignProperty(record, "qux.qaz", "abc");
assignProperty(record, "foshizzle", 10);

console.log(record.foo.bar.baz);
console.log(record.qux.qaz);
console.log(record.foshizzle);

function assignProperty(obj, path, value) {
    var props = path.split(".")
        , i = 0
        , prop;

    for(; i < props.length - 1; i++) {
        prop = props[i];
        obj = obj[prop];
    }
    
    obj[props[i]] = value;
    
}