Why is !null true when var is null per default

Why is JavaScript executing the code below even though the var is initially declared as null? The condition in the if-query is that the var interval is not null but it is, so actually it should not be executed.

let interval = null;

if (!interval) {
  setInterval(print, 1000);
}

function print() {
  console.log('Hi');
}

>Solution :

null is one of a few ‘falsy’ values in JavaScript, including NaN, false, 0, "" and undefined. When JavaScript is asked to coerce a value to bool, which if does, the value is checked against falsy values, but is otherwise considered ‘truthy’. Your null was falsy, you used ! to ‘not’ it, making it true.