In Javascript comparing values are not always as straightforward as one would expect. Overcoming that fear of which variables are truthy are sometimes is just as easy as learning which values are falsy. If you remember them (6 values) then you can easily know which values are true.
- NaN
- false
- undefined
- ”, “”, “ – the empty string either single quotes, double quotes or template literalts
- 0
- null
How do you remember these 6 falsy values in Javascript you say? People remember things differently and since all are unique there are many ways to remember.
Remember the simple things first, the one number i.e 0 (zero) is always false. That’s easy to remember right? Also false makes perfect sense to be…you guessed it: false.
So four values to go, look at this: null, NaN, undefined
Finally strings contain text, strings talk, but a string that doesn’t contain anything can’t talk, so it should be false.
The perfect order
- 0
- false
- null – NaN – undefined — becomes nullnandefined – null (and) undefined. Those are three values coerced into one to remember easily!
- empty strings – can’t talk, should be false then. ”, “”, “