<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title></title>
<meta http-equiv="X-UA-Compatible" content=" IE=edge, chrome=1">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" >
<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no, minimal-ui">
<meta name="keywords" content="">
<meta name="description" content="">
</head>
<body>
<input id="all_blocks" type="text" value="is105x1,is132x5,is123x1">
<input id="is105" type="text" value="1">
<input id="is132" type="text" value="1">
<input id="is123" type="text" value="1">
<script>
(function() {
var all_blocks = document.getElementById("all_blocks");
document.addEventListener("input", function(event) {
var input = event.target;
all_blocks.value = all_blocks.value.replace(new RegExp("(^|,)(" + input.id + ")x(.*?)(,|$)", "gi"), '$1$2x' + input.value + '$4');
});
})();
</script>
</body>
</html>