Truthy and Falsy values in JS

"Every value in JavaScript has an inherent boolean value. When that value is evaluated in the context of a boolean expression, the value will be transformed into that inherent boolean value."
The paragraph above is pretty dense with information. You should probably re-read it again.

Falsy values

A value is falsy if it converts to false when evaluated in a boolean context. For example, an empty String "" is falsy because, "" evaluates to false. You already know if...else statements, so let's use them to test the truthy-ness of "".

Here’s the list of all of the falsy values:

1. Boolean value false
2. number 0
3. number negative -0
4. BigInt 0n
5. empty string ""
6. null type
7. undefined type
8. NaN(stands for Not a Number).

There are eight falsy values in all of JavaScript! MDN
(at the time of writing this article)

Truthy values

A value is truthy if it converts to true when evaluated in a boolean context. For example, the number 1 is truthy because, 1 evaluates to true. Let's use an if...else statement again to test this out:

Here are some other examples of truthy values:

• true
• 42
• "pizza"
• "0"
• "null"
• "undefined"
• {}
• []

Simply put: if it's not in the list of falsy values, then it's truthy.

Be a little extra careful when working with the same element value but different element type. For example, 0 is a number while "0" is a string. Similarly null is different(falsy) from string "null"(truthy) and undefined(falsy) is different from string "undefined"(truthy)

Comparison operator

Even though as mentioned above that [] is a truthy value but behaves differently when used in conjunction with a comparison operator like ==, it evaluates to false. Likewise null is a falsy, but when used with a == operator evaluates to true. Similary for undefined and NaN.

That's all there is to this topic. For some people truthy & falsy values might be not of a big deal, but knowing how they behave can save you some real time instead of just scratching your head.Let me know if you guys have any questions. Happy Learning..