JSFiddle - React, Tailwind, and code Playground

JavaScript

var data, container, key, curHeading, heading, i, checkbox;

data = {"Heading 1":["Content 1","Content 2"],"Heading 2":["Content 1","COntent 2","Content 3"],"Heading3":["Content 1"]};

container = document.createElement("div");
for (key in data) {
    curHeading = data[key];
    heading = document.createElement("h4");
    heading.innerHTML = key;
    container.appendChild(heading);
    for (i = 0; i < curHeading.length; i++) {
        checkbox = document.createElement("input");
        checkbox.type = "checkbox";
        container.appendChild(checkbox);
        container.appendChild(document.createTextNode(curHeading[i]));
        container.appendChild(document.createElement("br"));
    }
}

document.body.appendChild(container);