HTML
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<link rel="stylesheet" href="array.css">
<script src="arrayIn.js"></script>
<title>Document</title>
</head>
<body>
<div class="inputpart">
<form class="" action="index.html" method="post">
<input type="text" name="array[]" value="" /><br>
<input type="text" name="array[]" value="" /><br>
<input type="text" name="array[]" value="" /><br>
<input type="text" name="array[]" value="" /><br>
<input type="text" name="array[]" value="" /><br>
<button id="btn" type="button" name="button" onclick="arrayIn()">Submit</button>
</form>
</div>
</body>
</html>
js
function arrayIn() {
document.getElementsById("btn").console.log("hello world");
}