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Editorial Team
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Asked: 2026-06-11T02:19:55+00:00

Every so often I run across someone using (!~val) instead of (val === -1)

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Every so often I run across someone using (!~val) instead of (val === -1) in situations where -1 is returned from a function (e.g. indexOf()).

To me, the logical NOT + bitwise NOT statement seems horribly unreadable when compared to the -1 comparison. Is there enough of a speed difference to warrant using one over the other? Or if not speed, some other reason that I’m missing to use a bitwise NOT instead of === ?

(Aplologies in advance if this is a dup., but I couldn’t find an answer to this exact question. Searching for “!~” doesn’t quite work in SO or Google)

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1 Answer

  1. Editorial Team

    No, they are definitely not the same.

    The bitwise conversion will do an implicit type coercion. The === operator checks for type equality.

    So these these two can give completely different results.

    var val = "-1";

(!~val) // true
(val === -1)  // false

    In a situation like this I think the intent and correctness of the comparison far outweighs any performance consideration. Decide what exactly you want to compare and use the right comparison for the job.

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