const regex = /\s*<script src="\/((\w+)[\w.\/]+)"><\/script>/g;
// Alternative syntax using RegExp constructor
// const regex = new RegExp('\\s*<script src="\\\/((\\w+)[\\w.\\\/]+)"><\\\/script>', 'g')
const str = `<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta http-equiv="Content-Security-Policy" content="default-src * data: gap: https://ssl.gstatic.com; style-src * 'unsafe-inline'; script-src * 'unsafe-inline' 'unsafe-eval'">
<meta name="viewport" content="width=device-width,initial-scale=1.0">
<title>atomic-project</title>
</head>
<body>
<div id="app"></div>
<!-- built files will be auto injected -->
<script src="/app.js"></script><script src="/app.js"></script><script src="/app.js"></script><script src="/app.js"></script></body>
</html>
`;
const subst = `\n<script>\n const $2Script = document.createElement('script');\n $2Script.type = 'text/javascript';\n $2Script.async = true;\n $2Script.src = '$1';\n document.body.appendChild($2Script);\n</script>\n`;
// The substituted value will be contained in the result variable
const result = str.replace(regex, subst);
console.log('Substitution result: ', result);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for JavaScript, please visit: https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions