<p>
	<input type="text" name="text" id="id_text_20171201" value="" placeholder="message" />
	<button onclick="send2line();">LINEに送る</button>
</p>
<script>
function send2line(){
	var text = document.getElementById("id_text_20171201").value;
	if (text === "") {
		alert("テキストが未入力です。");
	} else {
		location.href="line://msg/text/?" + encodeURIComponent(text);
	}
}
</script>