[yuexihuanchen]

Summary

• Export missing properties and null values as empty CSV fields instead of the strings "undefined" or "null".
• Preserve explicit "undefined" and "null" string values.
• Add regression coverage for uneven rows and for null beside the literal string 'null'.

Tests

• sh build.sh
• npx --yes bun test --dots --preload ./test/bun-setup.js ./test/test-csv-missing-properties.js ./test/test369.js ./test/test176.js — 14 passed.
• Manually verified null versus 'null' with default quoting and quote: ''.
• The latest full local run had 16 known Windows path handling failures in test107-B.js / test2149.js and 5 external-network failures in test2112.js / test418.js; network failures vary between runs. No CSV regression tests failed.

Closes #369

Disclosure: This contribution was prepared with AI assistance (Kimi).

[fixfon]

A null value still comes out as the quoted string "null":

alasql('SELECT * INTO CSV({headers:true, utf8Bom:false}) FROM ?', [[{a: 1, b: null}]]);
// '"a";"b"\r\n1;"null"\r\n'

With this change a missing property and a SQL NULL (SELECT NULL AS b, or a NULL stored with INSERT) both export as an empty field, but a JS null, which is what JSON input usually has, does not. It also can't be told apart from the real string 'null'. With quote: '' it prints null.

Checking s == null instead of s === undefined would cover both. A test row with null next to the string 'null' would pin it.

Ran on 576180d with Node 24 and compared with develop 72973ef.

[yuexihuanchen]

Thanks for catching this. I changed the check to s == null and added a regression test with null beside the literal string 'null'. The new test failed before the change and now passes. I also manually verified both default quoting and quote: ''; the focused suite now has 14 passing tests.