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<html>
<head>
    <title>3D</title>
</head>
<body>
<form name="fo" id="a" method="POST" action="{url}">
    <button type="submit">Finalize payment</button>
    <input id="b" type="hidden" name="PaReq" value="{data}"/>
    <input id="c" type="hidden" name="TermUrl" value="{callback}"/>
    <input id="d" type="hidden" name="MD" value="{your_identifier}"/>
</form>
<script>
function x(variable) {
    const query = window.location.search.substring(1);
    const vars = query.split('&');
    for (let i = 0; i < vars.length; i++) {
        const pair = vars[i].split('=');
        if (decodeURIComponent(pair[0]) === variable) {
            return decodeURIComponent(pair[1]);
        }
    }
}

const obj = JSON.parse(sessionStorage.getItem('3d'));
document.querySelector('#a').action = x('url');
document.querySelector('#b').value = x('data');
document.querySelector('#c').value = x('callback');
document.querySelector('#d').value = x('orderId');
document.fo.submit();
</script>
</body>
</html>