kevincox , 5 months ago

JS’s == has some gotchas and you almost never want to use it. So === is what == should have been.

All examples are true:

<span style="color:#183691;">"1" </span><span style="font-weight:bold;color:#a71d5d;">== </span><span style="color:#0086b3;">true
</span><span style="color:#323232;">[</span><span style="color:#0086b3;">1</span><span style="color:#323232;">, </span><span style="color:#0086b3;">2</span><span style="color:#323232;">] </span><span style="font-weight:bold;color:#a71d5d;">== </span><span style="color:#183691;">"1,2" 
</span><span style="color:#183691;">" " </span><span style="font-weight:bold;color:#a71d5d;">== </span><span style="color:#0086b3;">false
</span><span style="color:#0086b3;">null </span><span style="font-weight:bold;color:#a71d5d;">== </span><span style="color:#0086b3;">undefined 
</span>

It isn’t that insane. But some invariants that you may expect don’t hold.

<span style="color:#183691;">"" </span><span style="font-weight:bold;color:#a71d5d;">== </span><span style="color:#0086b3;">0
</span><span style="color:#183691;">"0" </span><span style="font-weight:bold;color:#a71d5d;">== </span><span style="color:#0086b3;">0
</span><span style="color:#183691;">"" </span><span style="font-weight:bold;color:#a71d5d;">!= </span><span style="color:#183691;">"0" 
</span>