Boolean value of JavaScript

JavaScript has a Boolean value of only two values, reserved words true and false.

Any JavaScript value can be converted to a Boolean value. The following values are converted to false:

Undefinednull0-0nan ""//empty string

All other values, including all objects (arrays), will be converted to true.

Take a look at an example, assuming that the variable o is an object or NULL, an If statement can be used to explicitly detect whether O is a non-null value:

if (o!== null) ...

The unequal operator "!==" compares o to null and results in a true or false result. Other:

if (o) ....

In the first case, the if code is executed only if O is not null, and the second case is less restrictive: only O is not false or any false value (such as null or undefined) when it executes the IF. Which statement to choose depends on what value is expected to be assigned to O. If you need to differentiate between null and O or "", you need to use an explicit comparison.

Boolean value of JavaScript