exec,
вложить картинки в контейнер с необходимой шириной
exec,
<!DOCTYPE html>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<style type="text/css">
#thumbs > div {
width: 2000%;
}
</style>
</head>
<body>
<div id="thumbs" style="border: 1px solid black; width: 350px; height: 50px; overflow: hidden"></div>
<script>
var thumbs = document.getElementById("thumbs"), div = document.createElement("DIV");
for (var i = 0; i < 10; i++) {
var img = document.createElement("IMG");
img.height = "50";
img.src = "http://farmeadow.com/wp-content/gallery/homepage/home5.jpg";
div.appendChild(img);
}
thumbs.appendChild(div)
</script>
</body>
</html>