gistfile1.js

document.getElementById("button_to_click").addEventListener("click", function anon(event) {
    this.removeEventListener("click", anon, false);
    var mobi_button = document.getElementById("element_to_append_to");
    var new_div = document.createElement("div");
    new_div.appendChild(document.createTextNode("Please wait while we prepare the book for you."));
    mobi_button.appendChild(new_div);
}, false);