function alertmsg() { alert("こんにちは"); } function addidmsg(ev) { var kadai_element = document.getElementById("hello"); if (kadai_element) { kadai_element.innerHTML += " こんにちは"; } } function show(ev) { var element = (ev.target||ev.srcElement); element.style.backgroundColor = "white"; } function addAll() { var i, item; var checks = document.getElementsByTagName("span"); for (i=0; i<checks.length; i++) { item = checks[i]; if (item.getAttribute("class") == "check") { item.addEventListener("click", show, false); } } } window.onload = addAll;