Null and undefined comparisons, and falsey values

Some languages have weird rules for null comparisons and falsey values; try to keep that in mind when coding weird edge cases. Some examples below.

PHP

$shadalooLeader = "M. Bison"
$ryu = '';

$ryu == null; // Evaluates to true
  
$ryu === null; // Evaluates to false
is_null($ryu); // Evaluates to true

JavaScript

let shadalooLeader = "M. Bison";
let ryu;

ryu === null; // False
ryu === undefined // True
ryu === "undefined" // True
ryu === void 0 // True