NULL, undefined check
// null, undefined check
if (x == null) {}
// null check
if (x === null) {}
https://stackoverflow.com/questions/28975896/is-there-a-way-to-check-for-both-null-and-undefined
// null, undefined check
if (x == null) {}
// null check
if (x === null) {}
https://stackoverflow.com/questions/28975896/is-there-a-way-to-check-for-both-null-and-undefined