requests.js

function createPost(event) {
    event.preventDefault();

    var inputs = document.forms[0].elements;
    var formData = {};
    formData.title = inputs.title.value;
    formData.post = inputs.post.value;

    createHTML(formData);

    //POST request
    var request = new XMLHttpRequest();
    request.open('POST','https://jsonplaceholder.typicode.com/posts');
    request.send(JSON.stringify(formData));

    request.onload = function() {
        console.log(request.response);
    }
}

function createHTML(data) {
    console.log(data);
    var container = document.getElementById('posts');

    var heading = document.createElement('h2');
    heading.innerText = data.title;
    container.appendChild(heading);

    if(data.post) {
        var postBody = document.createElement('p');
        postBody.innerText = data.post;
        container.appendChild(postBody);
    }
}

function requestTodo() {
    var request = new XMLHttpRequest();

    //specify verb and URL
    request.open('GET', 'https://jsonplaceholder.typicode.com/todos/1');

    //send request
    request.send();

    //response
    request.onload = function() {
        var response = JSON.parse(request.response);
        createHTML(response);
    }

}