<!DOCTYPE html PUBLIC>
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="ko" lang="ko">
<head>
<title></title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<meta name="viewport" content="width=device-width,initial-scale=1,user-scalable=no" />
<script type="text/javascript" src="jquery.min.js"></script>
<script type="text/javascript" src="qrcode.js"></script>
</head>
<body>
<input id="text" type="text" value="www.baidu.com" style="width:80%" /><br />
<div id="qrcode" style="width:100px; height:100px; margin-top:15px;"></div>
<script type="text/javascript">
var qrcode = new QRCode(document.getElementById("qrcode"), {
width : 100,
height : 100
});
function makeCode () {
var elText = document.getElementById("text");
if (!elText.value) {
alert("Input a text");
elText.focus();
return;
}
qrcode.makeCode(elText.value);
}
makeCode();
$("#text").
on("blur", function () {
makeCode();
}).
on("keydown", function (e) {
if (e.keyCode == 13) {
makeCode();
}
});
</script>
</body>
原文：http://www.cnblogs.com/gxw123/p/7053550.html