Automatic type conversion

For many programming languages, using a function on a value of the incorrect data type will result in an error. JavaScript's automatic type conversion feature may instead result in strange behaviour.

Boolean not (!) forces the operand to become a Boolean, and hence always returns either true or false.

In contrast, the values returned by || and && may not be Boolean values. These operators both use short-cut evaluation, and in doing so, return the value of the last expression evaluated. This value is expressed as true or false if it is a Boolean value and as a non-Boolean value otherwise.

Try to guess the results before clicking on the Run button.