418teapot , 4 hours ago

It’s kind of insane how bad this whole is-number thing is. It’s designed to tell you if a string is numeric, but I would argue if you’re ever using that you have a fundamental design problem. I hate dynamic typing as much as anyone else, but if forced to use it I would at least try to have some resemblance of sanity by just normalizing it to an actual number first.

Just fucking do this…

<span style="font-weight:bold;color:#a71d5d;">const </span><span style="font-weight:bold;color:#795da3;">toRegexRange </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#323232;">(minStr, maxStr, options) </span><span style="font-weight:bold;color:#a71d5d;">=> </span><span style="color:#323232;">{
</span><span style="color:#323232;">  </span><span style="font-weight:bold;color:#a71d5d;">const </span><span style="color:#323232;">min </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#0086b3;">parseInt</span><span style="color:#323232;">(minStr, </span><span style="color:#0086b3;">10</span><span style="color:#323232;">);
</span><span style="color:#323232;">  </span><span style="font-weight:bold;color:#a71d5d;">const </span><span style="color:#323232;">max </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#0086b3;">parseInt</span><span style="color:#323232;">(maxStr, </span><span style="color:#0086b3;">10</span><span style="color:#323232;">);
</span><span style="color:#323232;">  </span><span style="font-weight:bold;color:#a71d5d;">if </span><span style="color:#323232;">(</span><span style="color:#0086b3;">isNaN</span><span style="color:#323232;">(min) </span><span style="font-weight:bold;color:#a71d5d;">|| </span><span style="color:#0086b3;">isNaN</span><span style="color:#323232;">(max)) </span><span style="font-weight:bold;color:#a71d5d;">throw </span><span style="color:#323232;">Error(</span><span style="color:#183691;">"bad input or whatever"</span><span style="color:#323232;">);
</span><span style="color:#323232;">  </span><span style="font-style:italic;color:#969896;">// ...
</span>

Because of the insanity of keeping them strings and only attempting to validate them (poorly) up front you open yourself up to a suite of bugs. For example, it took me all of 5 minutes to find this bug:

<span style="color:#323232;">toRegexRange(</span><span style="color:#183691;">'+1'</span><span style="color:#323232;">, </span><span style="color:#183691;">'+2'</span><span style="color:#323232;">)
</span><span style="font-style:italic;color:#969896;">// returns "(?:+1|+2)" which is not valid regexp
</span>