The AND Operator (JS Demystified)

Question

Classical Meaning:

alert(true && true) // true
alert(true && false) // false
alert(false && true) // false
alert(false && false) // false

JS Quirks:

1. Reads from Left to Right
2. Convert Operand to Boolean (any value type)
3. Returns the First Falsy (original value)
4. Returns last value if all operands are truthy.

Examples:

alert(1 && null) // null
alert(2 && alert(1) && 3) // undefined
alert(1 && 2 && 3) // 3

Answer 1

@Marat the OR operator returns the first truthy value. Hence the following:

alert(1 || NaN) // 1
alert(1 || null) // 1
alert(1 || undefined) //1