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  • Ahmed Elgendy thinks this is interesting:

There are five falsey values in JavaScript:

undefined is falsey.

null is falsey.

0 is falsey.

The empty string is falsey.

NaN is falsey.

To remember which values are truthy and which are falsey, just memorize the five falsey values—undefined, null, 0, “” and NaN—and remember that everything else is truthy.


Cover of Head First JavaScript Programming


What are these five falsey values in Javascript?