Truthy and Falsy

Truthy Falsy

👨‍💼 We often need to decide if a value "exists" without comparing it to null or undefined. JavaScript treats some values as falsy, and everything else as truthy.

Falsy values:

false
0, -0, 0n
'' (empty string)
null
undefined
NaN

You can convert any value to a boolean with Boolean(value) or !!value.

🐨 Open

index.ts

. The starter provides these fixtures:

Name	Value
`username`	`'kent'`
`nickname`	`''` (empty string)
`age`	`0`
`email`	`'kent@epicweb.dev'`
`password`	`''` (empty string)
`notes`	`undefined`
`cartTotal`	`42`
`hasAcceptedTerms`	`false`

Create and export:

hasUsername — boolean for whether username is truthy
hasNickname — boolean for whether nickname is truthy
hasAge — boolean for whether age is truthy
hasNotes — boolean for whether notes is truthy
canCheckout — true only when cartTotal is truthy and hasAcceptedTerms is true
canCreateAccount — true only when hasUsername, email, and password are all truthy

Required exports

hasUsername, hasNickname, hasAge, hasNotes, canCheckout, canCreateAccount

Completion criteria

Each export must be a real boolean (typeof "boolean"). Use the fixtures and the falsy list above to reason about (or log) what each expression evaluates to—don't hardcode the answers.

💰 Convert values to booleans when you need a strict true/false.

📜 MDN - Truthy 📜 MDN - Falsy

03. Primitive Types/06. Truthy and Falsy (💪 problem)

Truthy and Falsy

Required exports

Completion criteria