TodayILearned - 2023-06-20

#TIL - Truthy vs. Falsy Values

These are two concepts that I felt like I knew but recently realized have been understanding very ‘vaguely.’ So let’s quickly do a TIL post on it.

Truthy

• Value that is considered true in a boolean context.
• Essentially, all values are truthy unless they are defined as falsy (what?)
• It’s actually easier to remember falsy values since there are fewer of them. So let’s move on.

Falsy

• empty string, ""
• false - duh
• 0, -0, 0n
• null
• undefined
• NaN

Previously during coding, I made the mistake of believing that an empty array [] or object {} was falsy just like an empty string "". So when my intended conditional if statement was not running in the way I expected, I was totally baffled. Well, that’s because I thought an empty {} was falsy!

Now that I think about it, it makes sense that {} and [] are truthy when "" is considered falsy, since the former are non-primitive values and the latter is primitive. So even though the inner contents are empty, the said array and object still points to a reference or point in memory.

Super quick TIL today, but something I’ve been meaning to document on my blog.