myautosaler, id не повторимо!!!
<!DOCTYPE HTML>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<script>
window.onload = function() {
document.querySelector('#raz1 input.plus').onclick = function() {
var theDiv = document.createElement('div');
theDiv.innerHTML = '<input type="text" class="tem" id="tem" >';
this.parentNode.insertBefore(theDiv, this.previousSibling);
getComputedStyle(theDiv).opacity;
theDiv.style.opacity = '1';
}
document.querySelector('#raz1 input.minus').onclick = function() {
this.parentNode.removeChild(document.querySelector('#raz1 div:last-of-type'));
}
}
</script>
</head>
<body>
<div id="raz1">
<input type="submit" value="create" class="plus">
<input type="submit" value="delete" class="minus">
</div>
</body>
</html>