I'll have to look into that. There are a few conflicts with real-time output and TIO's new features: 1. The response is compressed. 2. The response is (supposed to be) cached. 3. STDOUT and STDERR are separated.
The fact that scripts that time out currently don't generate any output at all is definitely fixable though.
@MartinEnder Not sure I've covered all cases, but it even preserves unprintable bytes on SE. Inside <pre><code>, 	 for a tab actually gives you a tab.
Something could definitely be done for multiple test cases. If I use DEFLATE.js instead of the browser's decompressor, each test case could be encoded in a different stream. Will take some work though.
For now, I should probably focus on unbreaking TIO on Firefox and Safari.
All of this would be so much easier if I could just use content-editable divs, but there's no way of disabling spell checking, auto-correction and auto-capitalization for those. sighs