function filterChange() {
let dropdownselection = document.querySelector("#dropdown_child").options[document.querySelector("#dropdown_child").selectedIndex].getAttribute("domain_filter");

d3.selectAll(".topic").style("display", "none")

d3.selectAll("." + dropdownselection + "-head").style("display", "block")

//This works because of the order of the classes - I think
d3.selectAll("." + dropdownselection + "domain" + "." + displayRadioValue()).style("display", "block")

}

function displayRadioValue() {

var ele = document.getElementsByTagName('input');
for (let i = 0; i < ele.length; i++) {
if (ele[i].type = "radio") {

if (ele[i].checked) {
// console.log(ele[i].value);
return ele[i].value;
}

}
}
}