JSFiddle - React, Tailwind, and code Playground

HTML

<form>Select your place:
    <fieldset id="mySelect">
        <input type="checkbox" value="[email protected]">l1
        <br>
        <input type="checkbox" value="[email protected]">l2
        <br>
        <input type="checkbox" value="[email protected]">l3
        <br>
        <input type="checkbox" value="[email protected]">l4
        <br>
    </fieldset>
</form>
<button type="button" onclick="displayResult()">Confirm Location</button>
<a id="send" href="mailto:">Send email</a>

<div id="myEmailList">

JavaScript

function displayResult() {
    var se = document.getElementById("myEmailList"),
        send = document.getElementById("send"),
        x = document.getElementById("mySelect"),
        l = [],
        list = x.querySelectorAll(":checked");
    for (i = 0; i < list.length; i++) {
        l.push(list[i].value);
    }

    send.href = "mailto:" + l.join(", ");
    se.innerHTML = l.join(", ");
}