How to check for null in JavaScript

check-null.md

• Checking for null is a common task that every JavaScript developer has to perform at some point or another
• The typeof keyword returns "object" for null, so that means a little bit more effort is required
• Comparisons can be made:
  • null === null to check strictly for null
  • null == undefined to check loosely for either null or undefined
• The value null is falsy, but empty objects are truthy, so typeof maybeNull === "object" && !maybeNull is an easy way to check that a value is not null
• Finally, to check if a value has been declared and assigned a value that is neither null nor undefined, use typeof
  • typeof maybeUndeclared !== "undefined" && (typeof maybeUndeclared !== "object" || !maybeUndeclared)