How can one troubleshoot and fix syntax errors when using JavaScript in PHP?

When using JavaScript within PHP code, syntax errors can occur if the JavaScript code is not properly formatted or enclosed within the correct syntax. To troubleshoot and fix syntax errors, ensure that the JavaScript code is enclosed within the appropriate script tags (<script></script>) and that any variables or functions are properly defined. Additionally, check for any missing or misplaced semicolons, parentheses, or curly braces within the JavaScript code.

<?php
echo "<script>";
echo "function myFunction() {";
echo "  var x = 5;";
echo "  var y = 10;";
echo "  var z = x + y;";
echo "  document.getElementById('demo').innerHTML = z;";
echo "}";
echo "</script>";
?>