The boolean type variable is used in control-flow, which we will get to in the next section.
The two types it may hold are
Usually you don't declare a variable, but you rather use an expression that evaluates to a boolean value - true or false.
nullsimply means nothing. It represents and evaluates to false. However, this does not mean it's empty.
var myVariable = ''; // myVariable is empty, but not null.
undefined means a variable that hasn't yet contained a value.
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