My suspicion is (though I haven't verified (because I don't have 'js' here))  that the subprocess (js) is using block buffering for its output when being run non-interactively...  in which case your readline might hang waiting for an end-of-line.

Unless you have control over the source of the subprocess to change such buffering behaviour, you're essentially out of luck.

In reply to Re: Diagnosing blocking io (or: finding the WHY of my Open2 woes). by almut
in thread Diagnosing blocking io (or: finding the WHY of my Open2 woes). by Socrates

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