I will be sharing bite sized learnings about JavaScript regularly in this series. Follow along with me as I re-learn JavaScript. This series will cover JS fundamentals, browsers, DOM, system design, domain architecture and frameworks.
console.log( null === undefined )
An important rule of checking type with null or undefined is that in the equality equation above, the result will be true only if both sides are either null or undefined.
This is helpful in checking against falsy values such as following -
let c;
console.log(c == null);
// true
console.log(c == undefined);
// true
console.log(0 == null);
// false
console.log("" == null);
// false
One caveat: == should be rarely used. This is a good use case for when == can be used. If you are unsure whether to use == or ===, use ===.