<script type="text/javascript" src="/path/to/script.js"></script><script src="index.js"></script><html>
<head>
</head>
<body>
<script type="text/javascript" src=es4.js></script>
</body>
</html>
<script src="PathToYourFile.js"> </script><script src = "index.js"></script><script type="text/javascript" src="pathToYourFile.js" ></script>//put it in last of body so javascript load after html element and javascript
//can change html element
<body>
<script src="index.js"></script>
</body><script src="script.js"><script type="text/javascript" src="yourFile.js"> </script><script src="name.js">
//put in your javascript here
</script><script type="text/javascript">
//JS code goes here
</script><script type="text/javascript">
//JS code goes here
</script><script>
// JS Here
</script><script type="text/javascript">
//JS code goes here
</script>