JSFiddle - React, Tailwind, and code Playground

JavaScript

function toHash(key, value){
    var parts = key.split('.').reverse(),
        i, foo = {}, bar = {};
    foo[parts.shift()] = value;
    bar = foo;
    for(i=0; i<parts.length; i++){  
        bar = {};
        bar[parts[i]] = foo;
        foo = bar;
    }
    return bar;
}
console.log(toHash('foo.bar.baz', 10));