What are truthy and falsy values in JavaScript?

In JavaScript, a value is considered “truthy” if it evaluates to true when evaluated in a boolean context. Conversely, a value is considered “falsy” if it evaluates to false when evaluated in a boolean context.

Here’s a breakdown of truthy and falsy values in JavaScript:

Truthy values:

1. Non-empty strings: Any string with at least one character.
2. Non-zero numbers: Any number except 0, including negative numbers and decimals.
3. true: The boolean value true.
4. Objects: Any non-null object or array, including empty objects and arrays.
5. Functions: Any non-null function.

Falsy values:

1. Empty strings: A string with no characters, represented as '' or "".
2. 0: The number zero.
3. NaN: Not-a-Number, a special value resulting from invalid operations.
4. false: The boolean value false.
5. null: The absence of any value or object.
6. undefined: A variable that has not been assigned a value, or a function with no return value.
7. Document.all: A legacy property that evaluates to false in modern browsers.

Here’s a simple illustration:

if ('hello') {
    console.log('Truthy'); // This will be printed
}

if (0) {
    console.log('Falsy');
} else {
    console.log('Falsy'); // This will be printed
}

Understanding truthy and falsy values is important in JavaScript, especially when working with conditional statements or type coercion.