Multi line strings in JavaScript are a bitch. At least till ES6. The canonical example for a node.js HTTPS server is:

// curl -k https://localhost:8000/
var https = require('https');
var fs = require('fs');
 
var options = {
  key: fs.readFileSync('test/fixtures/keys/agent2-key.pem'),
  cert: fs.readFileSync('test/fixtures/keys/agent2-cert.pem')
};
 
https.createServer(options, function (req, res) {
  res.writeHead(200);
  res.end("hello world\n");
}).listen(8000);

All fine and dandy as the sync operation doesn’t penalize the event loop. It is associated with the server startup cost. However, jslint yells about using sync operations. As the code is part of the boilerplate for testing http-get, refactoring didn’t make enough sense. Making jslint to STFU is usually the last option. The content of the files never changes, therefore it doesn’t make any sense to read them from the disk either. Inlining is the obvious option.

Couldn’t find any online tool to play with. Therefore I fired a PHP REPL, then used my PCRE-fu to solve this one. The solution doesn’t look pretty, but it gets the job done:

php > var_dump(preg_replace('/\n/', '\n\\' . "\n", file_get_contents('server.key')));
string(932) "-----BEGIN RSA PRIVATE KEY-----\n\
MIICXAIBAAKBgQCvZg+myk7tW/BLin070Sy23xysNS/e9e5W+fYLmjYe1WW9BEWQ\n\
iDp2V7dpkGfNIuYFTLjwOdNQwEaiqbu5C1/4zk21BreIZY6SiyX8aB3kyDKlAA9w\n\
PvUYgoAD/HlEg9J3A2GHiL/z//xAwNmAs0vVr7k841SesMOlbZSe69DazwIDAQAB\n\
AoGAG+HLhyYN2emNj1Sah9G+m+tnsXBbBcRueOEPXdTL2abun1d4f3tIX9udymgs\n\
OA3eJuWFWJq4ntOR5vW4Y7gNL0p2k3oxdB+DWfwQAaUoV5tb9UQy6n7Q/+sJeTuM\n\
J8EGqkr4kEq+DAt2KzWry9V6MABpkedAOBW/9Yco3ilWLnECQQDlgbC5CM2hv8eG\n\
P0xJXb1tgEg//7hlIo9kx0sdkko1E4/1QEHe6VWMhfyDXsfb+b71aw0wL7bbiEEl\n\
RO994t/NAkEAw6Vjxk/4BpwWRo9c/HJ8Fr0os3nB7qwvFIvYckGSCl+sxv69pSlD\n\
P6g7M4b4swBfTR06vMYSGVjMcaIR9icxCwJAI6c7EfOpJjiJwXQx4K/cTpeAIdkT\n\
BzsQNaK0K5rfRlGMqpfZ48wxywvBh5MAz06D+NIxkUvIR2BqZmTII7FL/QJBAJ+w\n\
OwP++b7LYBMvqQIUn9wfgT0cwIIC4Fqw2nZHtt/ov6mc+0X3rAAlXEzuecgBIchb\n\
dznloZg2toh5dJep3YkCQAIY4EYUA1QRD8KWRJ2tz0LKb2BUriArTf1fglWBjv2z\n\
wdkSgf5QYY1Wz8M14rqgajU5fySN7nRDFz/wFRskcgY=\n\
-----END RSA PRIVATE KEY-----\n\
"
php > var_dump(preg_replace('/\n/', '\n\\' . "\n", file_get_contents('server.cert')));
string(892) "-----BEGIN CERTIFICATE-----\n\
MIICRTCCAa4CCQDTefadG9Mw0TANBgkqhkiG9w0BAQUFADBmMQswCQYDVQQGEwJS\n\
TzEOMAwGA1UECBMFU2liaXUxDjAMBgNVBAcTBVNpYml1MSEwHwYDVQQKExhJbnRl\n\
cm5ldCBXaWRnaXRzIFB0eSBMdGQxFDASBgNVBAMTC1N0ZWZhbiBSdXN1MCAXDTEx\n\
MDgwMTE0MjU0N1oYDzIxMTEwNzA4MTQyNTQ3WjBmMQswCQYDVQQGEwJSTzEOMAwG\n\
A1UECBMFU2liaXUxDjAMBgNVBAcTBVNpYml1MSEwHwYDVQQKExhJbnRlcm5ldCBX\n\
aWRnaXRzIFB0eSBMdGQxFDASBgNVBAMTC1N0ZWZhbiBSdXN1MIGfMA0GCSqGSIb3\n\
DQEBAQUAA4GNADCBiQKBgQCvZg+myk7tW/BLin070Sy23xysNS/e9e5W+fYLmjYe\n\
1WW9BEWQiDp2V7dpkGfNIuYFTLjwOdNQwEaiqbu5C1/4zk21BreIZY6SiyX8aB3k\n\
yDKlAA9wPvUYgoAD/HlEg9J3A2GHiL/z//xAwNmAs0vVr7k841SesMOlbZSe69Da\n\
zwIDAQABMA0GCSqGSIb3DQEBBQUAA4GBACgdP59N5IvN3yCD7atszTBoeOoK5rEz\n\
5+X8hhcO+H1sEY2bTZK9SP8ctyuHD0Ft8X0vRO7tdt8Tmo6UFD6ysa/q3l0VVMVY\n\
abnKQzWbLt+MHkfPrEJmQfSe2XntEKgUJWrhRCwPomFkXb4LciLjjgYWQSI2G0ez\n\
BfxB907vgNqP\n\
-----END CERTIFICATE-----\n\
"
php >

This gave me usable multi line strings that don’t break the PEM encoding.

Update: shell one liner with Perl

cat certificate.pem | perl -p -e 's/\n/\\n\\\n/'