I was recently introduced to this book called I don't know Javascript by Kylie Simpson, where I am reading You Don't Know JS: Up & Going, the second chapter Of Javascript and I read about truthy and falsy values.

So what are truthy and falsy values?

Falsy values in javascript are some non-boolean values coerced (converted i guess) to boolean values.

Truthy values are values other than falsy values.

Before listing falsy values I would list the common primitive data types in javascript:

string, number, null, undefined, boolean

*symbols and bigint are skipped for now

So listing falsy values now :

• "" : empty string, type of STRING

• 0 : zero, type of NUMBER

• -0 : negative zero, type of NUMBER

• NaN: Not a Number, type of NUMBER

• null: null primitive data type

• undefined: again primitive data type

So out of 7 primitive data types, 3 of NUMBERS (0, -0 and NaN), 1 of STRING ("") and null and undefined are falsy values.

So for remembering purpose we can divide falsy values according to their primitive data types.