JavaScript logical operators

JavaScript logical operator NOT (!) and (&&) OR (| |)

Not (!) The type of the return value must be a Boolean value

The operand is also a Boolean value return value is: With the opposite Boolean value

and (&&)

1, two operands when the first is false or 0 or null or undefined or NaN, the second operand is not executed. Return: first operation arithmetic;

2, two operands when the first is an object or True, returns: the second operand;

OR (| |)

1, two operands when the first is false or 0 or null or undefined or NaN, a second operand is executed and returned: the second operand;

2, two operands are objects, run both objects, and return the first operand;

JavaScript logical operators