JSFiddle - React, Tailwind, and code Playground

JavaScript

var conversation = {
    'John': {
        1: 'Test message 1',
        2: 'Test message 2',
        'Reply': {
            3: 'Test message 3',
            4: 'Test message 4'
        }
    },
    'Jack': {
        5: 'Test message 5',
        6: 'Test message 6'
    }
};

function printValues(obj) {
    for (var key in obj) {
        if (typeof obj[key] === "object") {
            printValues(obj[key]);   
        } else {
            console.log(obj[key]);    
        }
    }
}

printValues(conversation);